Boil orange juice, chipotles, and vinegar in a saucepan, then simmer until reduced to 1/3 cup (15-20 minutes).

Remove sauce from heat and let cool.

Prepare charcoal or gas grill for cooking.

If using charcoal, open vents and light the charcoal.

Charcoal fire should be medium-hot (hand 5 inches above rack for 3-4 seconds).

If using gas, preheat grill on high for 10 minutes, then reduce to moderately high.

Combine coriander, cumin, chili powder, black pepper, and salt in a bowl.

Brush tuna with 1 tablespoon of olive oil and coat with spice mixture.

Grill tuna on oiled rack, turning to brown all sides, until browned outside but rare inside (8-10 minutes total).

Let tuna rest for 10 minutes.

Heat tortillas on grill until warm, about 1 minute per side, then wrap in foil to keep warm.

Toss jicama, cilantro, lime juice, remaining olive oil, salt, and pepper in a bowl.

Halve, pit, peel, and slice avocado into 1/2-inch-thick slices.

Place a tortilla on each plate.

Divide arugula, jicama mixture, and avocado among tortillas.

Slice tuna 1/4 inch thick and add to tacos.

Drizzle chipotle sauce over tuna and roll up tacos.