In a large, deep skillet, heat the oil and cook the lamb until browned on all sides. If the skillet is large enough, add the onion and garlic and cook 5 minutes longer, then transfer to a large pot. If the skillet is not large enough, remove the lamb to a large pot. Add additional oil to the skillet, if needed. Saute the onion and garlic 5 minutes, then add to the lamb. Add about 3 cups water. Bring the stew to a boil, reduce heat and simmer at least 1 1/2 hours. Add water if needed.

While the lamb is simmering, roast, peel and seed the green chiles.

Chop half the chiles and add to the stew. Put the other half in a blender or food processor with the tomato sauce and puree until smooth. Add the puree to the stew, along with the jalapenos or serranos, the oregano, and sage. About 10 minutes before the chili is done, add the fresh cilantro and salt. Taste and adjust seasonings.

When I make it, I use 2 large onions, usually 6 big cloves of garlic, at _least_ 2 pounds of green chiles, always use Mexican oregano, and as I usually purchase my cilantro and it goes funky so quickly in the refrigerator, I chop up the whole bunch to add. (If I'm making something like Xnipec at the same time, I'll buy another bunch - I really like cilantro). I simmer it at least 2 hours after the chiles are added (I get them ready before I brown the meat) until the lamb is _very_ tender, then I add the cilantro and simmer the last 10 minutes.