1/2 cup (1 stick) unsalted butter, softened
2 tablespoons lemon zest
1 tablespoon fresh lemon juice
1/2 teaspoon freshly ground black pepper
1/4 teaspoon garlic powder
Nonstick, nonflammable cooking spray
8 slices your favorite bread
4 tablespoons olive oil, divided
8 (6 to 8-ounce) 1-inch thick tuna steaks
Salt and freshly ground black pepper
Caramelized Lemon Slices, for garnish, recipe follows
Lemons
Sugar