New Mexican Chili Verde

Ingredients:
2 teaspoons olive oil
1/2 pound pork loin — cut into 1/2-inch chunks and remove all visible fat
3 small garlic cloves — finely minced
1 red onion — finely chopped (optional)

2 tablespoons flour — preferably masa flour
2 tablespoons cornstarch
4 tablespoons water

28 oz. New Mexican chiles — roasted, peeled, seeded, and finely chopped
1-2 tablespoons chopped jalapeno pepper — optional and preferably fresh