Heat the butter and vegetable oil in a large skillet, and cook the onion until translucent, stirring occasionally, about 5 minutes. Stir in the green and red peppers, and cook for 5 more minutes, then transfer the vegetables with a slotted spoon into a 2-quart baking dish. Stir the turkey meat into the hot oil left in the skillet, and cook until browned, about 8 to 10 minutes; place the turkey into the baking dish. Mix the mushrooms, apple, and garlic into the turkey and vegetables. Pour the white wine into the dish. With a small piece of kitchen twine, tie the sprigs of thyme, oregano, parsley, and sage into a little bundle, and drop it into the baking dish. Sprinkle with salt and pepper.
Cook in the preheated oven until the turkey is tender, 1 1/2 to 2 hours; remove the herb bundle before serving.