- 1 flank steak (about 2 1/2 pounds)
- 1/4 cup fresh lime juice from 2 to 3 limes
- 1 large onion (about 14 ounces), peeled and cut into 1/2-inch thick rounds (do not separate into rings)
- 2 large red bell peppers, or green bell peppers (about 10 ounces each) seeded and cut into large strips (see illustration below)
- 16 flour tortillas (10-inch)
1. Light large chimney starter filled with hardwood charcoal (6 quarts) and allow to burn until all charcoal is covered with layer of fine gray ash, about 20 minutes. Build modified two-level fire by stacking all of coals on one side of grill. Set cooking rack in place, cover grill with lid, and let rack heat up, about 5 minutes. Use grill brush to scrape cooking rack clean. Grill is ready when fire is hot.
2. Generously sprinkle both sides of steak with lime juice and salt and pepper to taste. Grill steak over coals until well seared and dark brown on one side, 5 to 7 minutes. Using tongs, flip steak; continue grilling until interior of meat is slightly less done than you want it to be when you eat it, 2 to 5 minutes more for rare or medium-rare (depending on heat of fire and thickness of steak).
3. Transfer meat to cutting board; cover loosely with foil and let rest for 10 minutes.
4. While meat rests and charcoal fire has died down to medium, grill onions and peppers, turning occasionally, until onions are lightly charred, about 6 minutes, and peppers are streaked with dark grill marks, about 10 minutes. Remove vegetables from grill and cut into long, thin strips; set aside. Arrange tortillas around edge of grill; heat until just warmed, about 20 seconds per side. (Take care not to dry out tortillas or they will become brittle; wrap tortillas in towel to keep warm and then place them in basket.)
5. Slice steak very thin on bias against grain; adjust seasonings with additional salt and pepper. Arrange sliced meat and vegetables on large platter; serve immediately with tortillas, passing salsa and guacamole separately.