Step 1In the bowl of a food processor, combine the chipotle chiles, garlic, cumin, green onions, cilantro, tomatoes, lemon, lime and orange juices, oil, salt and pepper. Purée.
Step 2Rub the marinade all over the skirt steak, then place in a large resealable plastic bag with the marinade and refrigerate 2 to 4 hours.
Step 3Remove the bag from the refrigerator 1 hour before grilling to allow the steak to come to room temperature.
Step 4Heat a discada or grill over high heat, and coat with a thin film of oil. Grill the steak until medium-rare, 4 to 6 minutes on each side. (For lower-heat burners, it might be easier to slice the steak prior to grilling to insure the pieces sear properly, and don’t simply simmer in their juices while cooking.) Remove the steak and slice crosswise across the grain into thin strips. Meanwhile, grill the sliced peppers and onions until charred and softened.
Step 5Remove the steak and vegetables from the discada. Lightly oil the discada and warm the tortillas on both sides. Serve immediately, along with the steak fajitas, vegetables, cheese and pico de gallo.