Step 1

Add the garlic, jalapenos, lime juice, orange juice, cilantro, olive oil, sugar, vinegar, 1 teaspoon salt and several grinds of pepper to a food processor and puree until very smooth.

Step 2

Cut the steak crosswise into thirds (skirt steak is typically long and skinny, so this will make the pieces more manageable when grilling). Place in a large resealable plastic bag, then pour in the marinade, flipping and massaging the steak to make sure it’s evenly coated. Remove as much air as possible, then seal the bag and refrigerate for 2 to 4 hours (any longer and the citrus juice will start to "cook" the steak).

Step 3

Preheat a grill for medium-high heat and brush the hot grates with oil. Remove the steak from the marinade, letting excess drip off, and season both sides with a pinch each of salt and pepper. Grill until nicely charred on the outside, 3 to 4 minutes per side for medium-rare. Transfer to a cutting board to rest, about 10 minutes. Thinly slice the steak against the grain, then serve with lime wedges.