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
• 1/2 cup chopped flat-leaf parsley
• 1/2 cup pitted, roughly chopped Castelvetrano olives
• 1 large shallot, peeled and diced
• 1/4 cup diced red bell pepper
• 3 tablespoons white wine vinegar
• 1/4 cup plus 2 tablespoons extra virgin olive oil