Marinate the steak the day before or morning of. When you are ready to cook it, drain and pat dry. Throw it on the grille or the stove top. Use a meat thermometer to ensure you cook to perfection.
While the steak cooks, assemble the beans. Only drain the pre cooked beans a little bit, saving a little juice. Add the beans to a sauce pan with olive oil, chopped onions and lime juice. Cook for 5-7 minutes until warm.
Assemble the tacos with your favorite toppings.