In a Dutch oven, sear the steak in hot oil. (Degrease the pan - if desired.) Throw in the onions, water to cover the meat, chile powder, cumin, Mexican oregano, garlic and tomato sauce. Season to taste with salt and black pepper. Stir the pot until well-incorporated. Bring the liquids to a hard boil, cover the pot, cut the heat to a slow simmer and braise for 1 1/2 hours. Stir the pot - on occasion.
If necessary, thicken the liquids with a slurry of Masa Harina, dissolved in water at 1 part Masa to 1 part water. Serve the chili in small bowls, topped with grated cheese.