Vegetarian Enchilada Casserole

Name: Vegetarian Enchilada Casserole
Prep time: 10 min
Cook time: 20 min
Total time: 30 min
Cuisine: Mexican
Ingredients: 1 tablespoon oil; 1 onion (diced); 1 yellow bell pepper, diced; 3 cloves garlic, minced; 2 cups red enchilada sauce; 2 cups corn; 1 can (15.5 ounce black beans, drained and rinsed); 1 can green chiles; 2 cups shredded Mexican cheese; 16 corn tortillas (cut in half); olives for serving (if desired); cilantro for serving (if desired); sour cream for serving (if desired)