6 tablespoons extra-virgin olive oil
1/4 cup fresh lemon juice
2 tablespoons drained capers
4 teaspoons liquid from capers in jar
4 teaspoons finely grated lemon peel
2 teaspoons finely minced fresh rosemary
1 teaspoon fine sea salt
Large pinch of dried crushed red pepper
6 6-to 7-ounce 1-inch-thick tuna steaks
Whisk first 8 ingredients in large bowl. Transfer mixture to an 8 by 8 in glass baking dish. Add tuna; turn to coat. Let marinate at room temperature 1 hour, turning occasionally. (Alternatively, chill 4 hours, turning occasionally, then allow to return to room temperature before continuing.
Bake in preheated 375 degree oven, turning as necessary, until done as desired.