Heat oven to 400°F.
In a large no stick skillet, heat oil over medium heat. Cook onion, celery, and bell pepper for about 3 minutes, stirring occasionally. Do not let brown! Stir in canned diced tomatoes, canned beans, steamed corn, peas and carrots, and green onions.
Transfer to a plate. In the same pan, cook ground turkey over medium heat for about 4-5 minutes, add taco seasoning and chili powder and let cook for additional 2 minutes, stirring occasionally. Add vinegar and cook for 1-2 minutes.
Add cooked vegetables to the pan, stir in nacho cheese, and spoon mixture into a 8-inch pie pan lined with a pie crust
Top with shredded cheese and then with second crust; seal edge and flute. Cut slits in several places in top crust. Brush top with a mixture of beaten egg yolk and heavy cream.
Bake for 30 to 40 minutes or until crust is golden brown. During last 15 to 20 minutes of baking, cover crust edge with strips of foil to prevent excessive browning. Let stand 5 minutes before serving.
Enjoy topped with guacamole (and sour cream, if desired) and a side of fresh salad.