Melt butter and olive oil in a large skillet over medium heat. Add onion and pepper and saute, stirring occasionally until nearly tender, about 5 minutes. Add the tortilla chips and continue cooking, stirring occasionally until chips are golden, about 2 minutes more.
Crack eggs into a large mixing bowl and whisk to combine whites and yolks. Add salsa, rice, beans, cumin, chile powder, salt and pepper and stir to combine. Pour egg mixture into the pan. Using a heatproof rubber spatula, cook, scraping to fluff into curds and prevent burning, just until wet-set. Add cheese and continue cooking until it is melted and gooey and eggs are firm.
Divide migas onto plates. Top with sour cream and onions and serve immediately, passing additional salsa at the table.
Rice, yellow onion, bell pepper, tortilla chips, salsa, pinto beans, sour cream, green onion and various spices.