Salmon Steaks with Red-Wine Butter

Combine wine, shallots, juice, vinegar, tomato paste, and bay leaf in a 1- to 2-quart heavy saucepan and boil over moderately high heat until mixture is thick and jamlike and reduced to about 1/3 cup, about 20 minutes. Discard bay leaf. Transfer mixture to a small bowl set in a bowl of ice and cold water and stir until cold to the touch, about 5 minutes. Remove from ice water and stir in zest, butter, 1/4 teaspoon salt, and 1/8 teaspoon pepper with a rubber spatula until incorporated. Preheat broiler. Line rack of a broiler pan with foil. Pat fish dry, then brush both sides with oil (2 tablespoons total) and sprinkle with remaining 3/4 teaspoon salt and 1/8 teaspoon pepper. Broil fish about 5 inches from heat, turning over once, until just cooked through, 8 to 10 minutes total. Top each steak with 1 to 2 tablespoons red-wine butter.