These flat iron steak tacos are marinated in an Aji (green sauce) mixture, then grilled hot and fast! While this recipe calls for flat iron steaks, you can substitute it with any flat steak including, flank, hanger, skirt, or sirloin flap steaks.
What is Aji?
Aji is a South American sauce used widely in Columbia and Peru. This sauce (or chunky salsa) can range from mild to super hot, depending on the region. We’ll be using the milder version to marinate the flat iron steaks for this recipe. However, we highly recommend that you make a double batch of the aji marinade for these flat-iron steak tacos. Use half of the mixture as a marinade, and reserve the other half to use as a topping for the tacos. Store it in an airtight container in the refrigerator until it’s time to use. Absolutely delicious!
Flat Iron Steak Tacos-The Ingredients:
- Flat iron steak, 2 pounds (or flat steak of choice)
- Corn tortillas
- Toppings: Lettuce, guacamole, queso, pico de gallo, cotija cheese, etc.
- Small onion
- Cilantro: sub with flat-leaf parsley
- Olive oil
- Salt and black pepper
How to make Flat Iron Steak Tacos:
- Marinade for flat iron tacos: Pulse marinade ingredients in a food processor. Add more lime juice or oil as needed. Make a double bath. Use 1/2 as a marinade for the steaks, and reserve the other 1/2 to use as a sauce for your flat iron tacos.
- Place the flat iron steaks in a resealable plastic bag. Pour the aji marinade over steaks and work it around the meat to get an even coating. Seal the bag and place it into refrigerator for 6-24 hours. Take the bag with steaks out of the fridge 20-30 minutes before cook time,
- Preheat your grill for medium-high heat, or 375 degrees F. Have your reliable instant-read thermometer nearby.
- Place the marinated flat iron steak onto the grill. Cook 5-7 minutes per side. See my steak temperature guide to determine your desired doneness.
- Wrap the tortillas in a large piece of aluminum foil. Place the packet on the grill for 5 minutes, turning once.
- Once the steak is cooked, remove it from the grill and set it onto a clean cutting board. Let it rest for 7-10 minutes. Remove tortillas and set them aside.
- Build your flat iron steak tacos: slice steak into thin (1/4″) strips and serve in warmed tortillas along with your favorite toppings.
- If you’ve made a double batch of the aji sauce, use the reserved half to serve with the tacos.
- Meat: If you cannot find beef flat iron steaks for these tacos , flank steak will suffice. Keep in mind that flank steak can be tougher than flat-iron and may require a longer marinating and cooking time. You can also use hanger, skirt, or sirloin flap steak for this recipe.
- Spice: If you love spicy food, add an extra jalapeno or habanero pepper sauce to the aji mixture. Experiment with the flavors and create something spectacular that suits your tastes.
Leftover Flat Iron Steak:
- Store the sliced steak in an airtight container in the refrigerator for 3-4 days.
- Make it a breakfast item! Chop the meat into bite-sized pieces and make a delicious breakfast hash with your leftovers!
- You can also scramble the steak with eggs and make flat iron tacos breakfast style.
- 2 pounds flat iron steak
- 12-14 corn tortillas
- 1 1/2 cups guacamole (lettuce, pico de gallo, queso, or cotija cheese)
- for marinade:
- 1 onion small, roughly chopped
- lime juice aim for two medium limes
- 2 jalapenos seeded and roughly chopped
- 1/4 cup cilantro
- 2 cloves garlic minced
- 1 tablespoon olive oil
- 2 teaspoons salt
- 1-2 teaspoons habanero pepper sauce (optional)
- 1 teaspoon black pepper
- Place all marinade ingredients into a food processor. Process until mixture is thick and smooth. Add more lime juice or oil if mixture remains chunky.
- Place flat iron steaks in a resealable plastic bag. Pour aji marinade over steaks and work it in making sure all surfaces of the meat are well coated. Seal bag and place into refrigerator for 6-24 hours.
- Preheat grill for medium-high heat.
- Remove steaks from bag and place onto grill. Cook 5-7 minutes per side or until steak reaches desired doneness. Place tortillas in a large piece of aluminum foil, wrap and place on the cooler part of the grill for about 5-7 minutes, turning once.
- Once cooked, remove steaks from grill and place onto a cutting board. Remove tortillas and set aside. Slice steaks into thin strips and serve in warmed tortillas with guacamole. If preferred, make a double batch of the aji sauce and reserve half to serve with the tacos.