Mackerel Provençal

I think mackerel is one of the most underrated fish in the United States. Its rich, full flavor makes it ideal for grilling.

For the tomato-olive vinaigrette:

• 4 medium tomatoes, diced
• 2 Tbs. pitted, chopped brine-cured black olives, like Niçoise
• 1 Tbs. chopped capers
• 1 Tbs. chopped fresh  flat-leaf parsley
• 2 Tbs. red-wine vinegar
• 3 Tbs. extra-virgin olive oil
• Kosher salt and freshly ground black pepper

For the mackerel:

• 1/4 cup Dijon mustard
• 4 tsp. finely chopped fresh rosemary
• 4 cleaned and boned mackerel (about 1/3 lb. each)
• Kosher salt and freshly ground black pepper
• Oil for brushing

In a mixing bowl, combine the tomatoes, olives, capers, parsley, vinegar, oil, salt, and pepper. Let stand while you prepare the mackerel. Heat the grill, making sure that it’s clean. The coals should be medium hot. Combine the mustard and rosemary and brush the mixture in the belly cavity of each mackerel; season with salt and pepper. Brush the outside of the fish with oil and sprinkle with salt and pepper. Grill over medium-hot coals until cooked through, about 5 minutes per side. Serve with the tomato-olive vinaigrette.