Heat the oil in a large skillet. Fry the tortilla strips until they are golden and crispy. Remove them with a spoon and set them aside on a paper towel.
In the same pan, sauté the onion, bell pepper, and jalapeño for about 5 minutes until soft. Keep the heat at medium so the veggies don’t burn.
While the vegetables cook, whisk the eggs in a bowl with salt and pepper until smooth. Ensure the yolks and whites are fully integrated.
Add the crispy tortillas back to the pan with the vegetables. Pour the eggs over the top and fold gently with a spatula until the eggs are mostly set.
Top the mixture with the shredded cheese and diced tomatoes. Fold once more to let the cheese melt into the warm eggs.
Remove from the heat and garnish with fresh cilantro and avocado slices. Serve immediately with salsa or hot sauce on the side.