Cook onions and garlic in 2 tablespoons of cooking oil until they are tender.
Add pimento, green chilies, and jalapeno peppers. Stir and cook until tender, and then set aside.
Cook tortillas one at a time, in about ¼-inch of cooking oil in a medium skillet until tortillas are crisp, turning once. Drain on paper towels and set aside.
Melt butter in another saucepan.
Stir in flour, chili powder, oregano, salt, and pepper.
Add the chicken broth all at once. Cook and stir until thickened and bubbly. Cook and stir for 1 minute more then remove from heat and stir in sour cream.
Arrange six of the tortillas, overlapping slightly, in an ungreased 3-quart rectangular baking dish.
Top with half of the chicken, half of the cheese, and half of the onion and peppers mixture.
Add another layer of tortillas, the remaining chicken, the remaining cheese, and the remaining peppers.