Step 1

To the bowl of a food processor or blender, add red onion, garlic, adobo sauce, ancho chile powder, olive oil, cumin, dried oregano, and salt and pepper to taste (I like 1 tablespoon salt and 1 1/2 teaspoons pepper). Blend until smooth. Pour into a measuring cup and add water to reach 1 cup.

Step 2

Place the steak in a large zipper-top plastic and add 1 cup marinade. Refrigerate overnight if desired. Let beef sit in the marinade for at least 30 minutes at room temperature before grilling.

Step 3

Heat 2 tablespoons oil in a large skillet until shimmering (or preheat a grill over medium-high heat). Add steak to the pan and cook, turning occasionally, until the temperature reaches 135 degrees for rare or 145 degrees for medium-rare. Depending on the size of your skillet, you can cook the steak in batches.

Step 4

Remove to a cutting board and tent with foil for 10 minutes. Chop into small pieces. Season to taste with salt. Serve on tortillas or in bowls with additional toppings as desired.