In large skillet set over medium heat, add oil. Add onion and garlic; cook, stirring occasionally, for 3 to 4 minutes or until softened. Add beef and taco seasoning. Cook, stirring occasionally and breaking up beef, for 6 to 8 minutes or until beef is starting to brown.
Warm chalupas in pan according to package directions.
Divide beef mixture among chalupas and top with sour cream, lettuce, tomato and cheese.
If desired, load up chalupas as well with guacamole, pickled jalapeño pepper slices, sliced pitted olives and hot sauce.