In a large bowl, combine beef and seasoning mix, mixing lightly but thoroughly. Shape into four 1/2-in.-thick patties.
In a large skillet, heat oil over medium heat. Add burgers; cook 4 minutes on each side. Remove from pan. In same skillet, add onion and peppers; cook and stir 5-7 minutes or until lightly browned and tender.
On the center of each tortilla, place 1/2 cup pepper mixture, 1 burger and 3 tablespoons cheese. Fold sides of tortilla over burger; fold top and bottom to close, forming a square.
Wipe skillet clean. Place wraps in skillet, seam side down. Cook on medium heat 1-2 minutes on each side or until golden brown and a thermometer inserted in beef reads 160°.