Start by gathering all your ingredients. Slice the avocado and set it aside. Whisk the eggs in a bowl until fully combined, and season with a pinch of salt and pepper.
In a non-stick skillet, melt the salted butter over medium heat. Once melted and bubbly, add the slices of sourdough bread. Toast until golden brown on both sides, about 2-3 minutes per side. Remove the bread from the skillet and set aside.
In the same skillet, pour in the whisked eggs. Allow them to cook undisturbed for a few moments until they start to set around the edges. Using a spatula, gently stir the eggs, pushing them from the edges toward the center. Cook until the eggs are just set but still soft and creamy. This should take about 2-3 minutes.
On one slice of toasted sourdough, spread the crème fraîche or sour cream. Top with the scrambled eggs, followed by the sliced avocado. Sprinkle with cotija cheese and fresh cilantro. Finish with a dash of hot sauce if desired. Place the other slice of bread on top to complete your sandwich.
Cut the sandwich in half if you’d like, and serve immediately while it's warm. Enjoy your delicious Scrambled Egg and Avocado Sandwich with a side of fresh fruit or a simple salad for a complete meal.