Season tuna steaks with salt and pepper and grill on an oiled rack set 5
to 6 inches over glowing coals 3 to 4 minutes on each side, or until just
cooked through. (Alternatively, tuna steaks may be grilled in a hot
well-seasoned ridged grill pan over moderately high heat.) Transfer tuna
to a platter and cool. In a large sealable plastic bag combine lemon
juice, thyme, and 1/4 cup oil and add grilled tuna. Marinate grilled
tuna, chilled, turning bag occasionally, at least 1 hour and up to 1 day.
If using canned tuna, drain tuna and in a bowl stir together with lemon
juice, thyme,1/4 cup oil, and salt and pepper to taste. In a bowl toss
together parsley, onion, and remaining 2 tablespoons oil and season with
salt and pepper. Pat roasted peppers dry. Halve focaccia horizontally and
layer one half with peppers, tuna, capers, and parsley salad. Top
sandwich with remaining focaccia half, pressing gently, and cut
lengthwise in half and crosswise into thirds to make 6 sandwiches. Cut
sandwiches in half diagonally and wrap tightly in plastic wrap. Chill
sandwiches at least 1 hour and up to 1 day. Makes 6 sandwiches.
