- 1 cup fresh orange juice
- 1 tablespoon minced canned chipotles in adobo (including sauce)
- 1 tablespoon distilled white vinegar
- 1 1/2 teaspoons ground coriander
- 1 1/2 teaspoons ground cumin
- 1 1/2 teaspoons chili powder
- 1 1/2 teaspoons cracked black pepper
- 1 1/2 teaspoons kosher salt
- 3/4 lb (1 1/2-inch-thick) sushi-grade tuna steak
- 2 tablespoons olive oil
- 4 (9- to 10-inch) flour tortillas
- 1 cup matchstick (1/8-inch-thick) pieces of jicama (from 1 small jicama, peeled)
- 1/4 cup coarsely chopped fresh cilantro
- 2 tablespoons fresh lime juice
- 1 firm-ripe California avocado
- 1 cup loosely packed arugula, coarse stems discarded
- Bring orange juice, chipotles, and vinegar to a boil in a 1- to 1 1/2-quart heavy saucepan, then reduce heat and simmer, stirring occasionally, until reduced to a generous 1/3 cup, 15 to 20 minutes. Remove from heat and cool.
- While sauce cools, prepare charcoal or gas grill for cooking. If using a charcoal grill, open vents on bottom of grill, then light charcoal. Charcoal fire is medium-hot when you can hold your hand 5 inches above rack for 3 to 4 seconds. If using a gas grill, preheat burners on high, covered, 10 minutes, then reduce heat to moderately high.
- While grill heats, stir together coriander, cumin, chili powder, black pepper, and kosher salt in a shallow bowl. Brush tuna on all sides with 1 tablespoon oil (total), then coat all sides evenly with spice mixture.
- Grill tuna on lightly oiled rack, uncovered, turning to brown all sides, until browned on outside but still rare in center, 8 to 10 minutes total. Let tuna stand 10 minutes.
- While tuna stands, heat tortillas on grill, turning over once, until warm, about 1 minute, and keep warm, wrapped in foil.
- Toss jicama with cilantro, lime juice, remaining tablespoon oil, and salt and pepper to taste in a small bowl. Halve, pit, and peel avocado, then cut into 1/2-inch-thick slices.
- Put a tortilla on each of 4 plates. Divide arugula, jicama, and avocado among tortillas, arranging evenly down center of each. Slice tuna 1/4 inch thick and divide among tacos. Drizzle chipotle sauce evenly over tuna and roll up tacos to enclose filling.