Method

1. Cut skirt steaks into 3 or 4 large pieces, to make them easier to marinade.
2. In a medium sized bowl, combine orange juice, lime juice, olive oil, garlic, cilantro, oregano, cumin, cayenne, salt and pepper. Add Marbled Beef skirt steak and thinly sliced onions and coat with the marinade.
3. Transfer to a resealable plastic bag and refrigerate 3-4 hours.
4. Remove skirt steak from the marinade and pat dry with paper towels. Discard remaining marinade.
5. Prepare your coals for direct grilling. Alternatively, you can cook steak with propane or in a pan, but it misses out on some the additional flavor that comes from the charcoal.
6. While your charcoal is igniting, caramelize onions. Add olive oil and butter to a skillet on medium low heat. Add thinly sliced onions and cook until the onions are a deep golden brown and very soft. Deglaze with vinegar and season with salt.
7. Grill Skirt steak for 2-3 minutes each side until it is medium rare to medium doneness. Remove from heat and allow the meat to rest for a few minutes before slicing against the grain.
8. Assemble sandwiches by slicing Ciabatta in half and spread with butter before layering arugula, Swiss cheese and sliced steak onto the bottom Ciabatta half. Pile a generous stack of the potato sticks and top with your remaining Ciabatta half.