Mexican Coca-Cola Marinated Beef Fajita Tacos

Living in Texas, there are three recipes everyone needs to know how to make –our freezer door margarita, Texas chili (no beans, of course), and fajitas. This recipe of beef fajita tacos is made with skirt steak marinated in a Mexican Coca-Cola to add a ton of caramelization to the steak when it’s grilled. Served with grilled onions and peppers in warm homemade tortillas and topped with grilled guacamole and spicy pico de gallo, this recipe for cola-marinated skirt steak fajitas is a must-have at your next weekend barbecue.

What are Fajitas?

Fajitas are a Tex-Mex dish made from marinated, grilled beef served on flour or corn tortillas, along with grilled onions and peppers. Fajitas are similar to the traditional Mexican tacos al carbon (tacos made from meat cooked over coals). Initially created around 1930 by vaqueros and ranch hands, the skirt steak and other throwaway parts of the cow were sometimes given to them as part of their pay. They would turn these pieces of beef into barbacoa, menudo, and what we know as fajitas. In the late 60s and early 70s, fajitas appeared on menus in various parts of Texas. Today, fajitas are made from steak, chicken, shrimp, and vegetables and then topped with salsa, guacamole, shredded cheese, and various other garnishes.

Key Ingredients and Substitutions

The ingredients for beef fajita tacos are straightforward, either being pantry staples or easy to find at any supermarket.

The complete ingredient list and measurements are listed in the printable recipe below.

• Skirt Steak: This cut of beef, just below the rib section, can be tough if not marinated, tenderized, and cooked correctly. If you can’t find skirt steak, you can substitute it with hanger steak, tri-tip steak, top sirloin steak, flank steak, or flat-iron steak. Read more about skirt steak and the differences between it and flank steak in our skirt steak vs flank steak post.
• Mexican Coca-Cola: You can use regular “American” or Mexican cola. Mexican cola is made with real cane sugar compared to fructose corn syrup used to make American. The cola helps tenderize the meat, and the sugar helps caramelize the steak as it cooks.
• Worcestershire Sauce: Besides adding umami flavor to the marinade, it is made with vinegar, which adds more acid to help tenderize the meat.
• Dona Maria Adobo: This adobo sauce is similar to mole sauce – spicy and sweet, with roasted spices. It is commonly found in most major supermarkets, or try making it.
• Mexican Oregano: Traditional oregano used in Italian and Mediterranean recipes is a part of the mint family, while Mexican oregano is not oregano. It is part of the verbena family and has bright floral and citrus notes. You don’t want to substitute regular oregano for Mexican because of the difference in flavor.
• Peppers: We grilled poblano peppers for this recipe but also love serving it with grilled red and yellow bell peppers.

How to Make Beef Fajita Tacos

Here are the quick step-by-step instructions with visuals; you can find the full instructions with the exact ingredients in the recipe card below.

Pro-tip: If you have a vacuum sealer, you can reduce the marinade time to an hour. Follow the directions of your equipment for best results, and let it marinate in the refrigerator.

1. Prep the Skirt Steak: The butchers usually fold up the skirt steak when they wrap it for you, so first, you’ll want to unfold it and place it on a cutting board. Using paper towels, pat both sides of the skirt steak dry, then sprinkle salt and ground black pepper on both sides of the meat, patting it in and setting it aside as you prepare the marinade. To get skirt steak into tender fajitas, we both hand-tenderized and marinated it for 4 hours. If the butcher did not mechanically tenderize the steak, you can use a meat mallet to tenderize it before placing it in the marinade. Starting from the center, strike the meat with the spiky or textured surface and work your way out to the edge.

2. Prepare the Skirt Steak Marinade: We recommend lightly toasting the cumin seeds in a small frying pan, moving it around frequently. When you begin to smell the warm flavor of cumin and first see a puff of smoke, they’re ready. In a medium bowl, combine the cumin seeds and Mexican oregano, then add the agave nectar, Worcestershire, and hot sauces and stir to combine. Next, add the adobo in little pieces and work it into the other ingredients with the back of a spoon until you have a consistent paste. Add the cola in batches using a whisk to incorporate it into the marinade. Finally, fold in the chopped cilantro and give it a final mix.

3. Marinate the Skirt Steak: Place the skirt steak into the zipper bag, then add the marinade, making sure there is good contact with all the surfaces. Press all the air before sealing, and lay on one side in the refrigerator. For best results, marinate the beef for 3-4 hours and flip it over at least a few times. Remove it from the refrigerator 30-60 minutes before grilling to allow it to come to room temperature, promoting more even cooking.

4. Grilling the Fajita: This cut of steak works well in most grill settings. While we prefer to grill outside using hardwood lump charcoal, it will still taste great off of a gas grill or even on a cast-iron grill on the stove in your kitchen. Preheat the grill to medium-high. Cook skirt steak for approximately 10-12 minutes per side or until the internal temperature is 130ºF. Remove it from the grill, place the steak on a flat cutting board or baking sheet, and tent it with aluminum foil. Let it rest for at least five minutes to prevent the juices from running out.

5. Slicing the Skirt Steak: Skirt steak is typically served sliced. Using a sharp knife, cut it against the grain. People who prefer beef on the medium side of doneness should get the pieces on either end. The middle section should be a near-perfect medium rare if you temp it and let it rest.

6. Serving: Over an open gas stovetop, with the flame on medium/low, heat the tortillas until lightly charred on the edges (approximately 10 seconds per side). Place the sliced grilled skirt steak and sliced peppers and onion on a serving platter and serve with the warmed tortillas and your favorite taco toppings such as grilled guacamole, spicy pico de gallo, sour cream, shredded cheese, salsa, chopped fresh cilantro, and lime wedges.

How to Slice Skirt Steak Against the Grain?

Skirt steak is a fibrous, tough cut of meat, so slicing it correctly is important. Cutting it against the grain produces a buttery, melt-in-your-mouth bite of beef. Slice it with the grain, and you will get a bite of beef that is tough, chewy, and almost inedible. The grain of a steak refers to the direction of the muscle fibers. The best way to slice skirt steak is by:

1. Find the grain. It is easier to identify the grain when the skirt steak is still raw, so before cooking the meat, take note of the way in which the muscle fibers run.
2. Place the steak on a cutting board. Position the steak on a clean cutting board so that the muscle fibers run parallel to the longest side of the cutting board and you.
3. Cut against the grain. Using a sharp knife, slice perpendicular to the steak so that it’s against the grain when you slice. The slices should be thin (approximately half an inch thick) and on a bias to get the most surface area of each slice.

What to Serve with Fajitas

Fajitas are traditionally served with Mexican-style rice and beans along with toppings. But the toppings are what are going to take your beef fajita tacos to the next level. Our toppings of choice are grilled guacamole, spicy pico de gallo, sour cream, shredded cheese, salsa, chopped fresh cilantro, and lime wedges. And don’t forget the appetizers and drinks. Our go-to’s are Tex-Mex queso, homemade tortilla chips, and a margarita. Our make-ahead freezer margaritas make entertaining easy or serve a strawberry margarita (frozen or on the rocks)

Make-Ahead and Storage

Make-Ahead: The marinade can be made up to 8 hours in advance. We recommend a marinade of at least 3-4 hours to make this in the morning and grill and serve the fajitas for an easy 30-minute dinner.

How to Store: Marinated skirt steak can be frozen both cooked and uncooked. Place uncooked steak and the marinade in a freezer-safe bag and remove as much air as possible. An uncooked marinated skirt steak will last up to 3 months in the freezer. Cooked skirt steak can also be stored in a freezer-safe container for up to 3 months. Leftover slices of skirt steak are great for fajitas, but they are the BEST steak sandwiches. You can also use them to top a salad. Store leftover grilled skirt steak in an air-tight container for up to 5 days.

How to Reheat: Allow frozen uncooked marinated skirt steak to defrost in the refrigerator in its marinade. Then grill per instructions. Cooked marinated skirt steak is best reheated in the oven to preserve some of the pink in the middle. Reheat for about 20 minutes at 200ºF. Avoid using the microwave since this will overcook and dry out the meat.

Recipe Tips and Notes

• Don’t skip the marinade. Skirt steak is a lean cut of beef and needs to be marinated or braised to increase tenderness. Marinating skirt steak gives it flavor but also breaks down the tough muscle fibers to produce a tender steak.
• The steak needs to rest. Resting allows the juices to redistribute and reabsorb into the meat. Cut too soon, and all those juices will seep out, resulting in drier slices of beef.
• Get a good sear. To achieve the best sear, make sure your grill is hot before adding the steak. Also, make sure the grill has been well-cleaned. Grease the grill well with oiled paper towels using tongs. 

Frequently Asked Questions