Combine seasoned salt, garlic salt, black pepper, cayenne pepper and oregano to make the fajita seasoning. Sprinkle two teaspoons of the seasoning over the sliced venison. Mix well, cover and refrigerate for 30 minutes.
Heat 2 tablespoons of oil in a heavy frying pan. Cook peppers and onion until starting to soften, then remove. Pour in remaining oil, then cook venison until browned. Return pepper mixture to the pan, season with remaining fajita seasoning and reheat. Serve with the warmed tortillas.