Skip to Content

Slow cooker onion tomato masala for Indian gravies

4.50 from 10 votes
Total: 5 hours 10 minutes
Serves 2 8 OZ. JARS


Slow cooker onion tomato masala for Indian gravies – a versatile masala that can be used for almost all the Indian recipes that calls for onion, ginger, garlic and tomato as base ingredients. Slow cooker method is a hit in my home because there is NO STRONG SMELL and it uses very less oil. Do you cook and store onion-tomato masala in bulk? If so then you will find this post helpful. If you are looking for Onion- tomato masala cooked over the stove/cooktop method – follow this link. 

PLEASE DO NOT COOK THIS MASALA WITH RED ONIONS – The pigment that give red onions its color reacts with the cooking environment – it  causes a chemical change and because of that (heat), red onions loses it’s color – they turn dark blue or green in color. 

RECIPE DETAIL – Peel, wash and ground onions, ginger and garlic to a fine paste. Add everything to the slow cooker, set the timer, cover and let it cook for 4 hours on HIGH setting. After the cooking time, remove the lid – masala will have some liquid left at the base, no worries, let it simmer with the lid off for another 1:30 minutes. Depending on the slow cooker model, cooking time may vary. This masala stays fresh in the refrigerator for at least a month.  In the slow cooker method, very less oil is added, so the oil will not separate from the masala.


Having guest over for dinner, no worries just throw in this masala with nearly any vegetable – Matar paneer, Aloo matar, Chicken recipes, Besan ke gatte, Lauki ke kofte, Palak Paneer ….the list is endless. This masala can be substituted for almost all the Indian recipes which calls for onion, ginger, garlic and tomato as base ingredients.

HOW TO USE THIS MASALA IN A RECIPE? If a recipe calls for 1 medium onion, 2-3 cloves of garlic, some ginger and 2 tomatoes then use 1/4 cup of cooked onion tomato masala and you are all set, follow rest of your recipe and your meal will be on the table in no time. Since there is very less oil added to this masala in slow cooker – so when you use it for a recipe, saute in oil for couple of minutes and that takes care of everything.

Follow this link to learn about how to store onion tomato masala.

Also try other slow cooker recipes – slow cooker ghee, slow cooker langarwali dal, slow cooker kadhi, slow cooker palak paneer, Slow cooker lobia.

Slow cooker onion tomato masala for Indian gravies

4.50 from 10 votes
A versatile masala that can be used for almost all the Indian recipes that calls for onion, ginger, garlic and tomato as base ingredients - slow cooker method.
Prep: 10 minutes
Cook: 5 hours
Total: 5 hours 10 minutes
Servings: 2 8 OZ. JARS


  • 4 big White Onions, crushed (or 4 cups)
  • 3 tablespoon Garlic paste
  • 3 tablespoon Ginger paste
  • 2 cups Homemade tomato puree
  • 1/4 cup Oil


  • Peel, wash and crush onions to a fine paste. I have used store bought tomato puree here.
  • Assemble: ginger-garlic paste.
  • Add onion, ginger and garlic paste to the slow cooker. Plug it in.
  • Add tomato puree.
  • Pour in oil.
  • Mix everything together.
  • Put the lid on and set the timer for 5:30 hours on HIGH setting. Cook masala covered for 4 hours.
  • After the desired cooking time, masala will have some liquid, open the lid and cook for another 1:30 minutes on HIGH SETTING. Depending on the slow cooker model, cooking time may vary.
  • Perfectly cooked masala is ready to be used for Indian gravies. Since there is very less oil added to this masala in slow cooker - so when you use it for a recipe, saute in oil for couple of minutes and that takes care of everything.
  • This masala stays fresh in refrigerator for at least a month.
Disclaimer: The nutritional information provided above is approximate. Variations may exist due to the ingredients/brands used. These numbers should be considered estimates, as they are not calculated by a registered dietician.
Author: Ruchi

Leave a comment

Your email address will not be published. Required fields are marked *

Rate the Recipe!


  1. Nishi says:

    Lovely way of teaching recipes.thanks.

  2. Alka says:

    I was looking for something like this for a while. Very nice and easy. Thanks al lot.

  3. aseem gauba says:

    Nice and easy and very useful when you are on busy schedules.I’ll advise to cook with white onions which gives great flavours…Great stuff.

    • RK says:

      Thanks for trying the recipe Aseem. Glad you found it useful. Agree, making this masala with white onions makes a huge difference.

  4. moma says:

    I have a question: I don’t plan on using onions. can this be made using just tomatoes, ginger and green chili?

  5. Hani says:

    I tried this several years ago with yellow onions. It was a disaster!! The onions turned green and the house was filled up with a weird smell…definitely not that of frying gravy masala. Don’t know what I did wrong. I never tried it again. Do you have any suggestions Ruchi?

    • RK says:

      Slow cooked onion tomato masala is very different from the cooktop one. The reason your mixture turned green was because of garlic. It release a sort of enzyme during cooking that makes the mix turn green when heated.It happens in the cooktop method too but it is sauteed until the masala is browned, so we do not notice that color. It is common, I have also noticed over the years that tomato puree gives a nice texture to the masala compared to the raw pureed tomatoes. Visit my facebook page to see reader’s success story.

  6. pooja says:

    Ruchi, I had been wondering for years why sone onions turn green when cookjng abd the. taste weird (sweetish bitter). Today yih solved this mystry! looking forward to trying this recipe!!

  7. Sorb says:

    how long can the frozen masala be stored for and still used safely: 1week? 1 month?

    • Sorb says:

      sorry, i just reread your article and it clearly says 1 month storage. another question is can we use salt instead of vinegar? would the vinegar change the taste of subsequent dishes using this masala?

      • Ruchi says:

        Thanks for stopping by! You don’t need to anything to this masala. It stores well without vinegar or salt.

  8. Priya says:

    What i is this slow cooker? Can we prepare this onion tomoato masala in regular cooker. If yes for how much time we need to cook it? kindly reply

  9. Supriya says:

    Hi ruchi…i want to know if all the ingredients- onions, ginger garlic and tomatoes and oil to be put at the same time in slow cooker or first brown the onions separately on normal stove and then put everything in slow cooker

  10. Shilpa says:

    Just noticed the photo of the finished masala has a red onion in it 😉 I use Spanish onions (red onion) to make masala all the time, fortunately I’ve never had a discoloration as you mentioned. Thanks for this recipe, I’m so happy to know masala can be made in the slow cooker! I have tomato and onion in the slow cooker now, and I haven’t puréed any of it (baby = shortcuts), I am confident it should be fine to be puréed at the end. I did sauté the onions before adding the tomato so as to get a slightly caramelised flavour. If this works out, I will make another batch and add ginger and garlic to it too. Fingers crossed!

    • Ruchi says:

      Thanks for sharing your experience with me, Shilpa.
      Glad you found this post helpful. 🙂

      • Shilpa says:

        Ruchi ji, this and many other recipes on your site have been amazing! Hubby and family have been enjoying everything I’ve made – thank you so much for sharing these!

      • Ruchi says:

        Pleasure is all mine Shilpa!
        I am glad you are enjoying my recipes. Thanks for sharing your wonderful feedback with me. 😍 😍

      • Shilpa says:

        Btw, I was able to make the masala using chunky pieces of tomato and onion, and puréed it at the end.

      • Ruchi says:

        That’s really great, thanks for sharing Shilpa!

  11. Vidushi says:

    Hi can I use fresh tomatoes instead of tomato puree… If not which brand of puree did you use

  12. HS says:

    Thanks for recipe. Either stove or slow cooker version how do you deal with the smell it generates when cooking?

  13. Sheetal says:

    Hi Ruchi. I’m based in the UK and keen to understand what you mean by tomato purée. Are you able to share any links to particular brands/types as I don’t think it is called the same thing here. Thanks.

  14. Rajeev says:

    I like your recipes. A question :
    I don’t throw away cilantro stem, I usually mix with tomatoes when making the purée in the food processor.
    Do you think it will affect the longevity of the masala if cilantro stem was blended in. Wondering some adverse effect would happen the same way you advise not to use red onion.
    Thanks for your recipes:
    Novice R B 😊

  15. Rajeev says:

    Hello Ruchi
    I followed your recipe step by step. I have an observation, I hope you can correct /advise.
    I used two cups of home made blended tomato paste, however the colour of masala turned out to be light bluish, it was as if there were no tomatoes. Once I added two small cans of store bought tomato paste and cooked some more, the colour turned out to be like the one you show in picture.

    You have asked for home made tomato purée, does the recipe require making a concentrated paste at home?


    • Ruchi says:

      Hello Rajeev,

      Thanks for trying the recipe. I am assuming you added garlic to the recipe. This color change happened because the dye in garlic, on exposure to the acid ( tomatoes), promoted the blue-green in the masala. While this chemical reaction/change in color may appear alarming, I assure you it is safe to eat ( unless the smell suggests otherwise).

      Another reason is if you used red onions. The reaction between sulfuric compounds in onion/garlic and acidic ingredients like tomatoes will promote the blue tinge hue in the masala. It’s absolutely ok to consume this masala, and your addition of store-bought tomatoes masked the color change and made it look appealing to the eyes. I hope this helps.

      • Rajeev Bhogal says:

        Thanks for replying Ruchi
        I am consuming the masala. No issues, the Color must have been from garlic because I used white onions.

        Explaining my follow up question again. Until I supplemented the masala with tomato paste the colour was very whitish with blue tint (garlic). Your recipe calls for 2 cups of Tomato purée, I had two cups of tomato paste by running through the blender. Your picture of tomato purée in instructions is much rich red in colour and so is your end product. I brought my end product to have the colour as yours only after I supplemented with two cans of tomato paste. So my question is that do we need to make tomato purée at home by concentrating the tomato pulp.

      • Ruchi says:

        You sure can try concentrating the tomato pulp; it will deepen the color and taste.
        The tomatoes used in this recipe were very pulpy with a rich, deep red color, which is what you see in the picture (blended into tomato purée). I hope that helps!