In a bowl, combine the chili powder, oregano, and salt. Pat the spices on the fish or meat. Heat the oil in a large nonstick skillet over medium heat. Cook 5 minutes per side for the salmon, 8 to 10 minutes per side for the chicken, or 15 minutes per side for the pork. (Reduce the heat if the spices begin to turn black.) Divide the fish or meat among 4 plates.