To make guacamole, place avocado and lime juice in a bowl and mash well.
Mix in sour cream and salsa. Reserve the guacamole in the fridge. Heat 1 Tbsp. of oil in a non-stick skillet set over medium-high heat. Rub chicken with chili powder, cumin, salt and pepper. Cook 3-4 minutes per side, or until cooked through. Cool chicken, and then thinly slice. Place in a bowl and toss with green pepper, cheese and cilantro. Divide mixture on one half of each tortilla shell. Fold over, and gently press down. Heat remaining oil in skillet set over medium heat. Cook Quesadillas 2-3 minutes per side, or until golden brown and cheese is melted. Cut into wedges and serve guacamole alongside for dipping.