Mexican Omelette

Name: Mexican Omelette
Ingredients: 1 1/2 tablespoons olive oil (divided); 3 tablespoons diced yellow onion; 3 tablespoons diced red bell pepper; 1 tablespoon diced jalapeño (seeds removed if not spicy); 1 teaspoon minced garlic; 3 tablespoons corn kernels (fresh, canned, or thawed frozen); 1/4 cup black beans (rinsed and drained); 1/2 Roma tomato (diced); 1 pinch dried Mexican oregano; 1 pinch ground cumin; Kosher salt (to taste); 2 large eggs (whisked); 1/4 cup shredded cheese (Mexican blend or Monterey Jack); Sour cream (for serving); Salsa, diced avocado, and chopped cilantro (for garnish, optional)