In a large pan over medium heat saute the onions and mushrooms in butter. Remove them to a plate once they are soft and the mushrooms have released most of their moisture. Reduce the temp to medium.
Beat together the eggs, salt and pepper. Give the pan some time to cool down before pouring in the beaten eggs. With a rubber spatula, turn the eggs... scraping the bottom of the pan. Cook until the eggs are just about set.
Top with the mushrooms, onions, steak and pepper jack cheese. Mix everything so the steak is heated through and the cheese is melted.
Divide the scrambled egg mixture among 4 flour tortillas and drizzle with the homemade steak sauce. Wrap and enjoy!