Place skirt steak in a deep dish. Whisk together all the ingredients for the marinade then pour marinade over the skirt steak. Cover dish and place in the fridge to marinate overnight.
Remove steak from marinade and dry off with a paper towel. Mix together the rub then press the rub into the meat until it’s completely coated. Set aside.
Place a large cast iron skillet over medium-low heat. Add 2 tablespoons of ghee along with the sweet potatoes and cook until sweet potatoes are browned and soft, about 12-15 minutes. Add salt, to taste.
Remove sweet potatoes, add 2 more tablespoons of ghee (if needed) then add peppers and onion. Cook until onion is translucent, about 10 minutes, then add garlic along with a pinch of salt and cook for another 2 minutes. Add sweet potatoes to the pan and toss to combined. Place on low heat.
Heat up a grill or grill pan to medium-high heat. Grease grill or grill pan then cook steak on both sides for 4-5 minutes per side, for medium-rare (depending on the thickness). Remove from grill and let rest for 5-10 minutes before thinly slicing against the grain.
Lastly, place tortillas over an open flame for 5-10 seconds to brown on both sides. Place thinly sliced steak on top of the tortilla along with some of the veggies, cilantro and sliced jalapeños!