First take a wok, add oil.
Add grind onions.
Stir till it gets brown.
Add ground tomatoes or puree.
Add salt as per taste, sugar 1/2 tsp, red chilli powder 1 tsp, dhaniya powder 1 1/2 tsp and dried mango powder 2 tsp. Stir it well (Mango powder gives a tangy taste and sugar balances the gravy flavour).
Add the washed chicken pieces in it.
Stir it properly so you mix the masalas well.
When the chicken starts getting soft, add butter in it. (Half of the butter 50 gms).
Stir again on a low flame.
Lastly when the piece start becoming tender, add rest of the butter.
Stir and enjoy with rotis or rice.