Prepare the Steak: In a large skillet, heat the vegetable oil over medium heat. Add the steak and half of the chopped onions. Cook until the onions are soft and the steak is browned.
Season: Sprinkle salt and pepper over the steak. Squeeze the juice of two limes over the steak and onions. Continue cooking until the steak is thoroughly cooked.
Prepare Tortillas: In another skillet, melt the butter. Lightly fry the mini corn tortillas until soft, about 1 minute on each side. Allow them to cool slightly before assembling.
Assemble Tacos: Double up the mini tortillas for each taco. Spoon the steak mixture onto the tortillas. Top with the remaining fresh onions and chopped cilantro.
Serve: Garnish with additional lime wedges and serve immediately.
