Gather the ingredients.
Migas ingredients in bowls

Position a rack in the center of the oven and heat to 350 F. In a medium bowl, add the eggs and salt. Whisk to combine. Set aside.
Eggs and salt in a glass bowl, stirred with a fork

Heat the vegetable oil in a medium nonstick, oven-proof skillet over medium heat. When the oil shimmers, add tortillas and fry, stirring occasionally, until crisp, about 2 minutes.
Tortilla slices in a pan with a wooden spoon, on a burner

Add onions and the bell peppers. Cook, stirring frequently until softened, about 5 minutes.
Tortilla strips, onions and peppers in a pan with a wooden spoon, on a burner

Add the eggs, stirring to combine the ingredients. Continue to cook, stirring often, until eggs are cooked until just set.
Eggs, tortilla strips, onions and peppers in a pan, on a burner

Top evenly with the Oaxaca cheese, transfer to the oven and bake until the cheese melts, about 8 minutes.
Melted cheese on top of the tortilla and eggs mixture in a pan

Remove from the oven and top with avocado, cotija cheese, and salsa, if using.