Ingredients

• 2/3 cup rice vinegar (not seasoned)
• 1/2 cup soy sauce
• 1/2 cup dry Sherry
• 1/2 cup dark amber or Grade B maple syrup
• 1 large firm-ripe California avocado
• 2 teaspoons fresh lemon juice
• 2 teaspoons extra-virgin olive oil
• 1/4 teaspoon salt
• 1/8 teaspoon black pepper
• 4 (7- to 8-oz) Spanish mackerel fillets with skin (about 1/2 inch thick)
• Accompaniments: rice; lemon wedges

Instructions

1. Briskly simmer vinegar, soy sauce, Sherry, and maple syrup in a 9- to 10-inch heavy skillet over moderately low heat until reduced to about 1/3 cup, 20 to 25 minutes. Keep warm.
2. Prepare avocado while sauce reduces: Quarter avocado lengthwise, then pit and peel. Cut lengthwise into 1/2-inch-thick slices, then gently toss together with lemon juice, oil, salt, and pepper in a small bowl.
3. Quarter avocado lengthwise, then pit and peel. Cut lengthwise into 1/2-inch-thick slices, then gently toss together with lemon juice, oil, salt, and pepper in a small bowl.
4. Glaze and bake fish: Preheat broiler. Line a large (15- by 10-inch) shallow baking pan with foil. 3Reserve about one fourth of glaze in a small bowl. Arrange fillets, skin sides down, in 1 layer in baking pan. Spoon about one third of remaining glaze over fillet, then spread with back of spoon to coat evenly. Broil fish 5 to 6 inches from heat, without turning, 2 minutes. Remove pan from broiler and coat with another layer of glaze, then broil 2 minutes more. Remove fillets from broiler and apply a third coat of glaze, then broil 1 minute more (for a total of 5 minutes). Remove from broiler and, with a clean spoon, apply reserved glaze. (Reserved glaze will not have touched uncooked fish.) Divide avocado salad among 4 plates, then serve fish alongside it.
5. Preheat broiler. Line a large (15- by 10-inch) shallow baking pan with foil. 3Reserve about one fourth of glaze in a small bowl.
6. Arrange fillets, skin sides down, in 1 layer in baking pan. Spoon about one third of remaining glaze over fillet, then spread with back of spoon to coat evenly.
7. Broil fish 5 to 6 inches from heat, without turning, 2 minutes. Remove pan from broiler and coat with another layer of glaze, then broil 2 minutes more. Remove fillets from broiler and apply a third coat of glaze, then broil 1 minute more (for a total of 5 minutes). Remove from broiler and, with a clean spoon, apply reserved glaze. (Reserved glaze will not have touched uncooked fish.)
8. Divide avocado salad among 4 plates, then serve fish alongside it.