In large nonstick skillet, heat oil over medium-high heat; stir-fry onion for about 3 min until softened. Add chicken, chili powder and oregano; stir-fry for about 3 min or just until chicken is browned all over. Add peppers and stir-fry for 2 min or until wilted.
Whisk flour into cream until smooth; stir into skillet. Simmer, stirring, for about 3 min or until liquid is bubbling and thickened. Stir in lime juice. Season with salt and pepper. Spoon filling along centre of each tortilla; add toppings. Fold up bottom of tortilla then fold sides to enclose filling.