Preheat the oven to 350 F.
Spray two oven-safe plates with nonstick spray. Warm red sauce in a medium pot on the stove.
In a small frying pan, heat frying oil until shimmering but not smoking.
Use tongs to place a corn tortilla in oil. Cook for about 10 seconds, flip, and cook for another 10 seconds. Your tortillas should still be soft.
Place on a paper towel lined plate while finishing the rest of the tortillas.
Dip a tortilla into the enchilada sauce so that both sides are coated. Place on serving plate. Sprinkle onions and cheese on top. Repeat with three more tortillas (for a total of four), ending with a layer of just cheese on top.
Repeat on the next serving plate.
Bake both plates for 10 minutes, until cheese is bubbly.
Pour remaining enchilada sauce and serve.