Heat milk in pan & bring it to boil. Remove from heat.
Add lemon juice. Stir slowly & gently until white curd forms on the surface & separates from whey.
Strain the milk. This will give you "chenna". Squeeze "chenna" to make sure that most water is extracted.
Knead "chenna" to make a smooth dough.
Make small balls if equal size and wrap each ball in gram flour.
Fry these "chenna" balls in oil until golden brown and keep aside.
Making gravy: Take a pan/kadai with specified oil and fry chopped onion until it turns pink.
Add turmeric powder & green chillies.
Add chopped tomatoes and fry well till the mixture starts separating from oil.
Now add milk in it & let it boil. Keep stiring in between.
After boiling for approx. 5-7 min, add the fried "chenna" balls & let it boil for another two min. Serve hot with roti.