ahi tuna recipe

(6 to 8 ounce) ahi tuna steaks (3/4 inch thick) For the marinade: 2 tablespoons toasted sesame oil 2 tablespoons soy sauce (or gluten-free tamari) 1 tablespoon grated fresh ginger 1 clove garlic, minced 1 scallion, thinly sliced (a few slices reserved for garnish) 1 teaspoon fresh lime juice