2 albacore tuna steaks, 1 inch thick
Coarse kosher salt and freshly ground pepper
Grated zest of 1 lemon
1 1/2 Tbs. extra-virgin olive oil, plus more as needed
1/4 cup fresh basil leaves, packed
1 Tbs. walnut pieces
Place the tuna on a plate. Sprinkle both sides with salt, pepper and the lemon zest. Brush with olive oil. Let marinate while preparing the sauce.
In the work bowl of a food processor, combine the basil, walnuts, 1/8 teaspoon salt and a generous amount of pepper. Process until finely ground. With the machine running, gradually add 1 1/2 tablespoons olive oil. Taste the sauce and adjust the seasoning with salt and pepper.
Prepare a charcoal or gas grill for direct-heat grilling over high heat. Add the tuna, cover the grill and cook as desired, about 3 minutes per side for rare. Transfer the tuna to 2 warmed individual plates. Top each with the basil sauce and serve right away. Serves 2; can be doubled.