Grilled Tuna Avocado Salad

INGREDIENTS

• 2 pounds very fresh tuna steak, cut 1-inch thick
• 4 tablespoons olive oil, plus extra for brushing
• 2 1/2 teaspoons kosher salt, plus extra for sprinkling
• 1/2 teaspoon coarsely ground black, plus extra for sprinkling
• 2 limes, zest grated
• 1 teaspoon wasabi powder (or paste)
• 6 tablespoons freshly squeezed lime juice (3 limes)
• 2 teaspoons soy sauce
• 10 dashes hot sauce (recommended: Tabasco)
• 2 ripe Hass avocados, medium diced
• 1/4 cup minced scallions, white and green parts (2 scallions)
• 1/4 cup red onion, small diced