Preheat the oven to 350°F. Spray an 8x8 casserole dish with non-stick cooking spray.
Set a medium saucepan over medium heat and add the oil. When the oil is hot, add the onion and green pepper. Cook for 3 minutes, until softened.
Add the beans and green chiles. Stir to combine and remove from heat.
Spread 1/2 cup of enchilada sauce onto the bottom of the baking dish.
Add 18 tortilla triangles to cover the sauce layer.
Add 1/3 of the bean mixture to cover the tortilla layer.
Sprinkle 2/3 cup of cheese over the bean mixture.
Repeat the layers two more times.
Cover with aluminum foil and bake for 35 minutes.
Remove the foil and sprinkle with the remaining 1/2 cup cheese. Bake, uncovered, for an additional 5 minutes, until the cheese is melted.
Garnish with cilantro and scallions. Serve warm.