Prepare sauce by mixing 1 cup sour cream and 1 cup salsa sauce, set the sauce aside.
Heat vegetable oil in a pan over medium heat, add jalapeno pepper, green pepper and garlic; fry for 2 minutes. Add mushrooms and fry 3-5 minutes. Then add chopped chicken and sauce; simmer until almost all liquid is absorbed (stirring occasionally). Set the mixture aside.
Take a non-stick pan, add a small amount of oil (about 1/2 teaspoon) and spread it around the bottom of the pan with a spatula; heat over medium heat. Place one flour tortilla in the pan. Sprinkle one layer of the cheese over half of the flour tortilla, top with one layer of mixture and again sprinkle one layer of the cheese on top.
Then slip spatula under the unfilled side, fold the flour tortilla over the filled side.
Fry until cheese melts and tortilla starts to brown and crisp. Then flip over the other side and wait until other side is done too. Remove from pan and place quesadilla on a cutting board; cut in half. Repeat procedure with the remaining tortillas.