How to Make It
In a small bowl, combine the cumin, oregano and garlic and onion powders, 1 teaspoon of salt and 1/2 teaspoon of pepper. Season the steaks on both sides with the spice mixture and rub them with the garlic puree.
In a large skillet, heat 1 tablespoon of the olive oil. Add 4 of the steaks and cook over high heat until browned, 1 minute per side; transfer to a plate. Repeat with the remaining olive oil and meat.
Reduce the heat to moderate and add the onions to the skillet, stirring until coated with oil. Cover and cook until just softened, about 5 minutes, stirring halfway through. Transfer the onions to a shallow bowl and cover with foil.
Add the stock to the skillet and simmer over moderately high heat for 1 minute, scraping up any browned bits from the bottom of the pan with a wooden spoon. Stir in the vinegar and butter and cook until the butter is completely melted and blended into the sauce.
Return the meat, any accumulated juices and the onions to the skillet and turn to coat and heat through. Transfer to plates, top with the cilantro and serve.