If needed, trim the fat and silver skin from the flank steak. (Your butcher or grocer may have already done this.)
2 pounds flank steak
Heat your oven to 350℉. Place the dried guajillo peppers on a baking sheet, and roast for 3 minutes to bring out the flavor.
3 dried guajillo peppers
Grid the peppers in a spice blender. To do so, remove the stems and seeds, and cut the pepper skins into pieces small enough to fit into your spice blender. Then grind until smooth.
Combine the resulting powder with the garlic powder, cumin, coriander, salt, and black pepper. Stir to combine, the rub on both sides of the flank steak.
2 teaspoons garlic powder, 1 teaspoon ground cumin, ½ teaspoon ground coriander, 2 teaspoon salt, ½ teaspoon black pepper
Place the steak, now covered in the dry rub, in a glass container with a tightly closed lid. Place in the refrigerator for 12 hours.
After marinating, you're ready to cook. Heat a cast iron skillet over medium-high heat for 2-3 minutes or until hot. Add the vegetable oil and swirl to coat the pan.
2 tablespoons vegetable oil
Carefully place the steak into the pan. Release the steak away from you, being careful not to splatter any oil by dropping the meat too quickly!
Cook for 4 minutes, Then, using a pair of tongs, flip the steak over and cook for another 3-4 minutes.
At this point, remove the steak from the heat and slice against the grain. If you find the meat is not cooked enough, you can return the slices to the pan and cook longer, until it reaches your desired doneness.
Toss sliced meat in a bowl with the lime juice and chopped cilantro. Serve straight, or use in tacos, burritos, or on a salad!
1 lime, 2 tablespoons fresh cilantro