2 lbs boneless lamb shoulder, cut into 1-inch pieces… I use chicken
1 T plus 1 t Madras curry powder - use any curry powder, I used Maharajah
1 t turmeric
1/2 t cayenne pepper
1 c plain whole-milk yogurt or low-fat
1 t garam masala

Place the above ingredients in a bag for four hours.

2 T olive oil
salt
2 onions, thinly sliced
2 T minced fresh ginger
2 garlic cloves, minced
2 bay leaves
1- 14-oz can tomato puree

Cilantro leaves, for garnish
Basmati rice and/or warm naan, for serving

Heat the oil. Cook the lamb/chicken and cook over high heat, stirring occasionally, until the lamb/chicken is browned/cooked.  Transfer to a bowl when done.
 
Cook onions over moderate heat until browned.  I used the food processer to puree the onions after I have browned them.   Then I mixed the pureed onions in the pan with the other ingredients:  ginger, garlic, and bay leaves and cook for 2 minutes. Add the tomato puree and bring to a boil. Season with salt.
 
Return the lamb/chicken mixture to the casserole. Cover partially and simmer over low heat until the lamb/chicken is very tender,  about 1 hour. Discard the bay leaves. Garnish with cilantro. Serve with rice and naan.