Buy the Inside Skirt Marinating Steak (not the Outside version) for the most tender option and ask that the silverskin membrane be trimmed off. If you can't find Skirt Steak a Flank Steak is a good substitute. Serve Skirt Steak sliced thinly with Fresh Tomato Salsa tucked into warmed tortillas or with a side of steamed rice and chili-spiced kidney or pinto beans.
Combine garlic, lime juice, oil, vinegar,cumin, chili powder, sugar and herbs in large resealable freezer bag. Pierce steak all over with fork; place into bag and refrigerate for 1 to 12 hours.
Remove steak from marinade and pat dry with paper towel; discard marinade. Season all over with salt and pepper.
Cook steak on lightly oiled grill over medium heat (400°F/200°C); close lid and cook, for 6 to 8 minutes, turning at least twice, for medium-rare doneness 145°F(63°C).
Remove to cutting board; tent with foil and let stand about 5 minutes before carving into thin slices across the grain. Serve with Fresh Tomato Salsa.
Fresh Tomato Salsa: In medium bowl, combine 2 medium tomatoes, (seeded and diced), 1 small avocado (diced), 1/2 onion (minced), 2 cloves garlic (minced), 1 jalapeno pepper (seeded and diced), juice from 1 lime, 2 tbsp olive oil and handful of fresh herbs such as oregano, basil and/or cilantro (chopped). Season with some granulated sugar, salt and pepper to taste.