Raw tuna antipasto

• Juice of 4 lemons 
• ½ cup red wine vinegar 
• 1 small shallot or onion, peeled and thinly sliced 
• 2 celery stalks, thinly sliced 
• 2 tablespoons dried oregano 
• ¹⁄3 cup extra-virgin olive oil 
• Salt and black pepper 
• 3 tablespoons capers packed, well rinsed
• 2 lemons, thinly sliced into rounds and halved 
• 2 pounds tuna steak, thinly sliced 
• ¹⁄3 cup minced flat-leaf parsley 
• Crusty, grilled bread slices for serving

Preparation:

Combine all the ingredients except the thinly sliced lemons, tuna, parsley, and bread in a rectangular glass dish large enough to hold the tuna steaks in a single layer. Add the tuna steaks and coat them in the mixture. Cover and marinate the fish for several hours or overnight, turning the pieces once or twice while they marinate. To serve as part of an antipasto, arrange a bed of shredded lettuce on a shallow platter and place the tuna slices, overlapping on top of the lettuce. Pour the marinade over the fish and sprinkle with the parsley. Arrange the lemon slices along the platter in an attractive manner. Serve at room temperature with crusty bread slices.