Rinse and soak chana dal in 1 cup of water for 3 hours. Soaking helps to aid in digestion.
After the soaking time, soaked lentils will swell in size. Discard the soak water and rinse the soaked dal well with tap water.
Transfer the lentils to a blender. Blend the dal until coarsely ground.
Transfer the lentils to a mixing bowl. Add onions, spinach, ginger, green chilies, peanut powder, cilantro leaves, curry leaves, and all the spices.
Use your hands or a spoon to mix the spices into the lentils thoroughly. Mix until all ingredients are combined.
Separate the dal vada mixture into 12 equal portions. Shape each portion into a ball. Then, gently flatten the ball into a vada. Use your fingers to smoothen the edges of the vada.
Repeat the process with the rest of the mixture.
Heat oil in a pan. To check if your oil has reached the frying temperature, put the end of a wooden spoon in the oil. If the oil starts bubbling around the spoon, then the oil is ready. Add dal vada to the hot oil. Fry dal vada on medium heat for 4-6 minutes per side.
Work in batches. Do not overcrowd the pan. Depending on the pan size fry 4-5 vadas at a time. Fry until the dal vadas are deeply golden in color, turning them halfway through the cooking.
Once cooked, transfer the dal vada to a paper towel-lined plate to soak up excess oil. Repeat this step until all the vadas are fried.