Beef Fajitas

Steps

1. Combine olive oil, soy sauce, lime juice, red pepper flakes, cumin, green onion, and brown sugar in a blender. Blend until smooth.
2. Pour marinade into a gallon size zip-top plastic bag. Add skirt steak and seal, removing as much air as possible. Refrigerate for at least 1 hour, preferably 24 hours or more.
3. Remove steak from marinade and place down as close as possible to coals of a preheated charcoal grill. Cook one side until the internal temperature is 125°F (51°C). Flip and allow to cook until the internal temperature is at least 145°F (63°C) in the thickest part. These temperatures are enough to safely cook the meat, you may like it more well done.
4. Remove and cover immediately, allowing at least 3 minutes to rest. You may wish to immediately wrap tightly with aluminum foil and remove to a low heat area of the grill or a low heat oven to keep ready for less-than-immediate use.
5. Meanwhile, place a 9–10-inch (23–25 cm) cast-iron skillet down on the coals (or a stove).
6. Once pan has heated, toss sliced peppers and onions with vegetable oil. Place in the skillet and cook for at least 2–3 minutes. They should be cooked to a moderately soft state on high heat with some browning evident. A small amount of water can be added, and the pan covered, to partially steam the vegetables if desired. Remove and keep warm.
7. Slice steak as thinly as possible across the grain.
8. Serve fajitas with tortillas, salsa, guacamole, and lime wedges (see notes).