Heat oil in a large frying pan over medium-high heat. Add brown onion, capsicum and garlic. Cook, stirring, for 2 minutes or until slightly softened. Add beef mince. Cook, breaking up with a wooden spoon, for 5 minutes or until browned and cooked through.
Add beans, corn and taco seasoning. Cook, stirring, for 1 minute or until fragrant. Add sauce and spring onion. Cook, stirring, for 2 minutes or until heated through. Season with salt and pepper.
Meanwhile, cook rice following packet directions.
Heat tortillas following packet directions. Place tortillas on a flat surface. Divide beef mixture along the centre of each tortilla. Top evenly with rice and Mexican cheese. Roll up tightly to enclose filling. Wrap burritos in foil. Bake for 5 minutes or until cheese melts. Serve the burritos with sour cream and lime wedges.