Remember the Seinfeld episode where his girl friend feeds him mutton and he chews and puts them into his coat pocket and Elaine being chased by the street dogs?
Mutton is a little harder, chewier and so most Americans dislike them. So you don’t find them in the grocery stores normally and available only at the ethnic stores. Mutton is not Lamb. Lamb is what you normally get here. But once if you are accustomed to mutton, it is a tiny chance you would like lamb and vice versa. Lamb is from the sheep and mutton is from goat – both very different animals.
However there has been an increase in mutton production in U.S, as there has been an increase in immigrant population who prefers mutton. Maybe the stores will start to carry them and you don’t have to go in search of this meat at ethnic stores.
We have goat farms here and we can even choose the goat and they would kill and prepare it for us. So we are lucky to get the freshest of the fresh. I usually buy one whole goat and divide the meat and store it in my freezer.
If you have a choice, buy the leg part of the mutton.

For 4 cups of cleaned mutton, mix 1 cup of coarsely chopped onion, ¼ cup of ginger garlic crushed, 1 sprig of curry leaves, 1 coarsely chopped tomato, 2 tsp of coriander powder, 2 tsp of meat masala powder, 1 tsp of chili powder, ½ tsp of turmeric, enough salt.
Mix well and marinate and keep aside for half an hour and then cook them in a pressure cooker or in a pot. If using pressure cooker, you need to know mutton in U.S takes more time to cook than beef. Usually in India it is the other way, beef takes time to cook. This is what I have normally seen in U.S. It takes the time to cook toor dal in a pressure cooker. Do not add water. The water from the meat will cook the mutton.
Heat 1 tbsp of oil, sauté 1 sprig of curry leaves, sauté and brown 1 cup thinly diced onion, add the cooked mutton and mix and boil in medium heat until the curry thickens to your preferred consistency.
Serve with rice or roti.