In a mixing bowl, add 1 cup of moong dal and ½ cup of poha. Wash them thoroughly and soak for 3–4 hours.
In another bowl, combine 1 cup of rava with 1 cup of buttermilk. Mix well and let it rest for 10 minutes.
Once the moong dal is well soaked, drain the water and transfer it to a mixer jar. Add ½ cup of water and grind into a smooth paste.
Add the ground moong dal paste to the soaked rava mixture and mix well.
Heat 2 tablespoons of oil in a pan. Add 1 teaspoon of mustard seeds, 2 chopped green chilies, and ½ cup of chopped onion. Sauté until the onions turn soft.
Add ½ cup of chopped capsicum, ½ cup of chopped tomatoes, and salt to taste. Mix well and sauté for 2–3 minutes.
Add 1 teaspoon of red chilli flakes and ½ teaspoon of black pepper powder. Mix well.
Transfer the prepared tempering (tadka) to the batter and add ½ cup of chopped coriander leaves. Mix everything well.
The batter should have a medium-thick, ribbon-like pouring consistency.
Just before making the chilla, add ½ teaspoon of baking soda and 1 teaspoon of lemon juice. Mix gently until well combined.
Heat a tawa and grease it lightly with oil. Sprinkle a few sesame seeds over the surface. Pour a ladleful of batter onto the tawa and spread it slightly to make 4–5 small chillas at a time.
Cook the chillas on a medium-low flame until they are golden and crispy on the bottom. Flip and cook the other side until crisp and evenly cooked.
Serve the hot moong dal chillas with tomato ketchup or green chutney.