Ingredients

• 3 large onions, peeled and cut lengthwise into wedges, leaving root ends intact
• 1/4 cup olive oil
• Kosher salt and freshly ground black pepper
• 1/4 cup balsamic vinegar
• 1/3 cup fresh lime juice
• 3 pounds skirt steak
• 1 tablespoon ancho chili powder
• 1 tablespoon ground cumin
• 1 tablespoon ground coriander
• 24 flour tortillas
• 1 1/2 cups fresh cilantro
• Roasted Tomatillo Salsa, recipe follows
• 3 pounds fresh tomatillos or 6 (11-ounce) cans tomatillos
• 10 fresh serrano chiles
• 6 garlic cloves, unpeeled
• 2 onions, cut into wedges
• 1 cup fresh cilantro leaves
• 1 tablespoon plus 1 teaspoon kosher salt
• 2 teaspoons freshly squeezed lime juice

Instructions

1. Special equipment: Metal skewers or a grill basket
2. Prepare grill for cooking.
3. Thread onions onto skewers (or put in grill basket), then brush with 1 tablespoon oil and season with salt and pepper. When fire is medium-hot (you can hold your hand 5 inches above rack for 3 to 4 seconds), grill onions, turning occasionally, until tender, 16 to 20 minutes. Transfer to a cutting board. When just cool enough to handle, cut onions into 1-inch pieces and toss with vinegar in a bowl. Season with salt and pepper. While onions are grilling, stir together the lime juice and remaining 3 tablespoons oil in a shallow dish, then add steak and marinate at room temperature, turning once, 10 minutes.
4. Pat steak dry, then rub with chili powder, cumin, and coriander and season with salt and pepper. Grill steak on lightly oiled grill rack, turning once, 6 to 10 minutes total for medium-rare. Transfer to cutting board, then let stand 5 minutes before cutting diagonally into thin slices.
5. While steak is standing, toast tortillas directly on grill rack, turning once, until puffed slightly and browned in spots, about 1 minute total. Serve steak, onions, cilantro, and salsa all wrapped in tortillas.
6. Preheat broiler.
7. If using fresh tomatillos, remove husks and rinse under warm water to remove stickiness. If using canned tomatillos, drain and measure out 4 cups. Broil fresh tomatillos (do not broil canned), chiles, garlic, and onions on rack of a broiler pan 1 to 2 inches from heat, turning once, until softened and slightly charred, about 8 minutes.
8. Peel garlic and pull off tops of chiles. Puree all ingredients in a food processor.
9. Yield: 6 cups