Cut the leftover steaks into ½-inch cubes. Transfer to a medium bowl. Add soy sauce, ketchup, dried crushed oregano, and vegetable oil. Marinate at room temperature for 20 minutes. Add the lemon juice at the last-minute.
In a small bowl, mix the onion and cilantro together. Set aside.
In a large pan over medium-high heat, add ½ tablespoon oil. Add the steaks and cook until warm through and slightly browned. Taste and adjust with salt if needed. Transfer to a medium bowl.
Meanwhile, start on the tortillas. Reheat them up over the open flame on the stove over medium heat until slightly brown, but still soft on both sides. Watch carefully because the tortillas can be burnt easily. Transfer the cooked tortilla to a tortilla warmer or a plate with an aluminum-foil-cover.
When everything is ready, put tortillas on serving plates and top with steaks and onion topping. Serve immediately with salsa verde or salsa.
Notes
If you want to try this recipe, but you don’t have any leftover Grilled College Marinated steaks. You can start with ¾ pound raw rib eye cap or rib eye steaks. Cut them into ½-inch cubes. Marinate them in ¼ cup ketchup, ¼ cup light beer, 3 tablespoons soy sauce, ¾ teaspoon dried crushed oregano, and ½ teaspoon vegetable oil for 20 minutes. Add 1½ tablespoons lemon juice just before cooking.
Tortillas can also be reheated on a pan over the stove. Cook until both sides start to puff.
I served the tacos with salsa verde that I bought from Trader Joe’s.