"This is a Tex-Mex-like enchilada sauce that I made up to take advantage of the prickly pear fruit that is so plentiful in the fall. The sauce has a tangy, barely sweet flavor with surprising depth. The red juice makes the sauce a pleasant pink color that my kids love. Serve with rice and refried beans."
Place prickly pear in a fine-mesh strainer set over a bowl. Mash with a potato masher to extract juice. Discard seeds and pulp.
Preheat oven to 400 degrees F (200 degrees C).
Heat oil in a large skillet over medium heat. Add chicken; cook and stir until juices run clear, 5 to 8 minutes.
Divide cooked chicken among 6 tortillas. Top with mozzarella cheese. Fold in opposing ends and roll up tortillas. Place seam-side down in a casserole dish.
Bake in the preheated oven until cheese is melted and tortilla edges are crisp, about 15 minutes.
Melt butter in a saucepan over medium-low heat. Add onion, bell pepper, garlic, and salt; cook and stir until very tender, about 5 minutes. Pour in prickly pear juice, water, lemon juice, bouillon cube, cornstarch, and pepper sauce; whisk until cornstarch dissolves into the sauce.
Bring sauce to a simmer over medium heat. Stir in sour cream. Simmer until flavors combine, about 3 minutes. Remove from heat; stir in parsley. Spoon sauce over tortillas.