Wash the chilka moong dal thoroughly and soak it overnight or for at least 8 hours. Drain all the water before using.
Add onion, garlic, ginger, green chilli, cumin seeds, salt, and coriander leaves to a mixer jar.
Blend until smooth.
Add besan and curd to the ground dal mixture.
Mix thoroughly until no lumps remain. The batter will appear slightly thick at this stage.
Gradually add water while stirring. The batter should have a pourable consistency similar to dosa batter.
Let the batter rest for 10 minutes.
Heat a non-stick or cast-iron tawa. Lightly grease with oil or butter.
Pour one ladleful of batter onto the hot tawa.
Spread gently in a circular motion to create a medium-sized chilla. Do not spread too thin.
Cover and cook for 2 to 3 minutes.
Apply a little ghee on top. Carefully flip the chilla. Cook for about 1 minute on the second side.
Spread a thin layer of tomato ketchup. Top with chopped onion, tomato, capsicum, and carrot. Sprinkle grated cheese and oregano generously.
Cover the pan again. Cook for another 2 minutes until the cheese melts and the vegetables become slightly tender.
Serve Moong dal chilla hot with green chutney, ketchup, or your favorite dip.