Using a meat mallet, pound the steaks until they're 1/4-inch thin. Pour the mojo marinade and spices. Marinate for at least 20 minutes.
In a large skillet, heat oil at medium-high heat. Remove steaks from the marinade, shaking off any excess, and place them on the pan. Cook them for 1-2 minutes per side until browned.
Reduce heat to medium-low heat. Add the onions and sauté them for 2-3 minutes until softened. Serve steak with onions. Enjoy!