Heat 1 tablespoon oil in a 12-inch skillet over medium-high heat. Add the beef and cook until well browned on both sides. Remove the beef from the skillet. Pour off any fat.
Heat the remaining oil in the skillet. Add the onions and cook until tender, stirring occasionally.
Stir the picante sauce in the skillet and heat to a boil. Return the beef to the skillet. Reduce the heat to medium. Cook the beef for 2 minutes for medium or until desired doneness.
Easy Substitution: You can substitute strip or rib steaks for the sirloin.