Grilled Mackerel with Tomato, Fennel, and Capers

1. 1Place all of the ingredients in a small, nonreactive bowl and stir to combine; set aside.

For the fish:

1. 1Heat a grill pan or outdoor grill to medium high (about 375°F to 425°F).
2. 2Meanwhile, brush the tomatoes and fennel all over with half of the measured olive oil and season with salt and pepper; set aside.
3. 3When the grill is ready, place the tomatoes and fennel on the grill and cook uncovered until grill marks form, about 3 to 4 minutes. Flip the vegetables and cook until grill marks appear on the other side, about 3 to 4 minutes more. Remove to a cutting board.
4. 4When the vegetables are cool enough to handle, cut and discard the cores from the fennel. Chop both the fennel and tomatoes into 1-1/2-inch pieces and place in a medium saucepan. Add the fish broth or clam juice, garlic, and saffron and stir to combine. Bring to a boil over medium-high heat. Reduce the heat to medium low and simmer until the vegetables have softened, about 20 minutes. Keep warm while you grill the fish. (If you’re using a grill pan, use several layers of paper towel to wipe the pan clean before grilling the fish.)
5. 5Heat the grill to medium high. Rub the grates with a towel dipped in olive oil.
6. 6Pat the mackerel fillets dry with paper towels. Brush both sides with the remaining measured olive oil and season both sides with salt and pepper. Place the fillets on the grill skin-side down and cook until grill marks appear, about 2 to 3 minutes. Flip the fillets with a flat spatula and cook until grill marks appear on the other side and the fish is cooked through, about 2 minutes more. Remove the fillets to a plate and tent with foil.
7. 7Add the parsley to the warm tomato-fennel mixture and stir to combine. Taste and season with salt and pepper as needed.
8. 8Divide the tomato-fennel mixture among 4 rimmed serving plates or shallow bowls and top each serving with a piece of mackerel. Top the fish with about 1 tablespoon of the tapenade (you will have some left over), sprinkle with the caperberries or capers, and serve immediately.