This flavorful appetizer is heartierthan other variations
Heat 1/2 to 3/4 cup oil (enough to cover tuna) and the lemon slices in a small saucepan over very low heat until warm. Generously salt tuna steak. Poach tuna in oil, turning once, until opaque on the outside but still a bit pink in the center, about 15 minutes. Remove tuna from pan, reserving oil; flake fish with a fork. Pass poaching oil through a fine sieve into a medium bowl; stir in flaked tuna, lemon zest, and capers. Season with pepper. Spoon mixture onto bruschetta slices, and drizzle with some of the poaching oil.