In a large skillet, heat oil. Add onion and red pepper and cook over medium heat, stirring often, until vegetables are lightly browned, about 4 minutes. Add garlic and cook 1 minute. Remove from heat and let cool slightly.
In medium bowl, combine cooked vegetables, ground beef, lime juice, chili powder and salt. Using wet hands, form into 4 ovals about 2 inches wide and 4 1/2 inches long.
Place patties in center of oiled grill set 4 to 6 inches from coals. Cook, turning once, until browned, about 4 minutes.
Transfer burgers to outside edge of grill and continue grilling, turning once, until burgers are cooked through and meat springs back when pressed lightly with a finger, 8 to 10 minutes.
Meanwhile, wrap tortillas in aluminum foil and place on sides of grill to heat through. Place warm tortillas and bowls of salsa and guacamole on table.
Let each guest place a burger on a tortilla, top with salsa
and guacamole, roll up and enjoy.