Rinse and soak the mung dal, urad dal, rice, and fenugreek seeds in warm water for 30 minutes or in room-temperature water overnight.
Drain out the soaking water completely.
Add the soaked dal and rice to a blender along with cottage cheese, water, cumin seeds, ginger, green chili, and salt.
Blend into a smooth batter.
Stir in the baking soda just before cooking.
Before making each uttapam, preheat the cast iron pan over low to medium heat for a few minutes. Sprinkle a few drops of water, if it sizzles and evaporates quickly, the pan is ready. Lower the heat, wipe the surface with a damp paper towel, then rub half an onion dipped in oil across the pan. This helps cool the surface slightly and creates a natural non-stick layer.
Pour about ½ cup of batter for each uttapam, spreading it slightly to form a 7-inch round.
Sprinkle chopped onion, tomato, and cilantro on top. Gently press down the topppings with a silicone spatula. Cook on low-medium heat for 3 to 4 minutes and then carefully flip the uttapam over.
Cook for an additional 2 to 3 minutes or until the veggies start to get a slight char. Take out the Uttapam from the hot pan.
Repeat the process of making Uttapam with the remaining batter. Makes 4 uttapam.