Cook the chopped drumsticks, tomatoes and onion in the vegetable stock until done.
Strain the cooked veggies through a sieve to extract the gravy. Keep the drumstick puree aside.
Prepare white sauce using flour, butter and milk. First, melt butter and add maida slowly. Switch off the burner and pour milk into the mixture, stirring constantly, until a thick consistency is obtained. Add a pinch of pepper, sugar and required salt. Your white sauce is ready.
Add the drumstick puree into the white sauce. Season with required salt and pepper.