Bring chicken stock to a boil in a large pot, add lentils, and reduce heat to a gentle simmer.
While lentils are cooking, dice two onions. Add the butter and onions to a skillet, saute over medium heat until transluecnt. Stir the onions occationally to prevent burning.
When the liquid has reduced to bellow the level of the lentils, add the salt, cumin, chili powder, oregano, tomatoes, and green chilies. Then add the sauteed onions, and any drippings remainng in the skillet. (This would be a good point to steam rice and prep your veggie sides.)
Simmer together to meld the flavours. Once the are compeltely cooked, stir in one cup of shredded cheese. Use the remaining the cheese for garnish at the table.
These lentils are great served over rice, but would also be delicious with just veggies and maybe a squash side. You can also omit the cheese altogether for frugality's sake - it's tasty either way!Extra-old cheese is also known as extra-sharp cheese depending on where you live.