In skillet, heat oil over medium-high heat; fry onion, garlic, salt and pepper until softened, about 3 minutes. Add chicken, jalapeño, red pepper, beans and salsa; cook, stirring, until chicken is no longer pink inside, about 10 minutes. Let cool.
Spoon about 3/4 cup (175 mL) of the filling down centre of each tortilla; sprinkle each with 1/4 cup (50 mL) of the cheese. Fold in bottom edge, then sides; roll up. Place, seam side down, in greased 13- x 9-inch (3 L) glass baking dish. Sprinkle remaining cheese over top.
Bake in 400°F (200°C) oven until golden and hot, and cheese is melted, about 15 minutes. Serve with sour cream.