Preheat grill to 400 degrees F.
Wash and pat dry the tuna steaks
. Season with salt and pepper and brush both sides with olive oil. Place tuna on hot grill
each side for 2 minutes for rare. If you prefer well done, cook the tuna an additional 2 to 3 minutes per side. Remove from skillet and let it rest.
Into the bowl of a food processor
, add the garlic, basil
leaves, pine nuts, salt, and pepper. Pulse
until finely chopped. With the blender
still running, slowly pour 1/2 cup of olive oil. Check for a thick, yet smooth consistency, adding more oil if necessary. Transfer to a bowl and stir in 1/2 cup Parmesan
Slice the tuna across the grain and on a bias into 1/2-inch thick slices. Place the slices on a serving plate and drizzle
with lemon juice. Sauce
tuna with pesto