Grilled Tuna with Castelvetrano Olive Relish - Fresh-Pressed Olive Oil

Ingredients

• 4 tuna or swordfish steaks, each about 6 ounces
• Extra virgin olive oil
• Salt and freshly ground black pepper
• 1 fennel bulb, trimmed, sliced into 1/4-inch wedges
• 2 leeks, cleaned and cut into 1/2-inch rounds
• 2 lemons, sliced into thin rounds, plus wedges for serving