Fennel-crusted Ahi Tuna with Lemon Aioli Over Couscous

INGREDIENTS
2 teaspoons fennel seeds
1 teaspoon coriander seeds
1 teaspoon whole black peppercorns
1 1/2 teaspoons kosher salt, divided
1/3 cup mayonnaise
2 tablespoons fresh lemon juice
3 tablespoons chopped fresh chives
4 garlic cloves, minced, divided
1/2 cup extra-virgin olive oil, divided
1 carrot, peeled, coarsely chopped
1/4 cup chopped red onion
2 teaspoons chopped fresh thyme
2 1/4 cups water
1/2 pound sugar snap peas
2 cups couscous
2 tablespoons chopped fresh dill
2 1/2 pounds ahi tuna steaks (about 1 1/4 inches thick)

METHOD
Combine first 3 ingredients in heavy small skillet. Toast over medium heat until fragrant, shaking skillet occasionally, about 3 minutes. Grind spice mixture in spice grinder. Transfer to bowl; mix in 1 teaspoon salt.

Whisk mayonnaise, lemon juice, chives, and half of garlic in small bowl. (Can be made 2 days ahead. Store spice mixture airtight at room temperature. Cover and refrigerate lemon aioli.)

Heat 2 tablespoons oil in heavy large skillet over medium-high heat. Add carrot and onion and sauté until crisp-tender, about 3 minutes. Add thyme and remaining garlic and sauté 1 minute. Add 2 1/4 cups water and remaining 1/2 teaspoon salt; bring to boil. Add sugar snap peas and cook until crisp-tender, about 1 minute.

Using slotted spoon, transfer peas to plate. Immediately add couscous to water in skillet and stir to combine.

Cover and remove from heat. Let stand 5 minutes. Fluff couscous with fork. Transfer to bowl and cool completely. Mix in sugar snap peas and dill. Season to taste with pepper. (Couscous can be made 2 hours ahead. Let stand at room temperature.)

Prepare barbecue (high heat). Coat tuna with 6 tablespoons oil. Sprinkle with spice mixture. Grill tuna until seared outside and rare in center, about 4 minutes per side. Refrigerate uncovered for 1 hour, then cut into 1/2-inch-thick slices. Spoon couscous onto plates. Top with tuna and drizzle with lemon aioli.