Procedures Add the lamb to the marinade and mix well.
Lightly roast the cumin seed and coriander seed by frying with no oil for a minute or so, stirring constantly. This can be skipped if need be. Refrigerate for 3-24 hours while mixing every few hours as convenient. Finely chop the onions and potatoes and saute them for 5 minutes in the butter. Grind these and combine them into a paste with the other spices, the garlic, ginger and the vinegar.