Grilled Mackerel with Walnut Agrodolce

For fish, in clean container, cover mackerel fillets with kosher salt. Let stand 8 to 10 minutes.

Wash off salt off with cold water and pat dry. (This can be done 6 to 24 hours in advance; cover and keep refrigerated until ready to cook.)

Meanwhile, prepare agrodolce: Preheat sauté pan over medium heat and add olive oil. Add shallots; cook until translucent. Add garlic and celery; cook 2 to 3 minutes.

Stir in golden raisins, coconut sugar and balsamic vinegar. Cook until vinegar is reduced by half. Add walnuts and lemon zest; remove from heat. Stir in walnut oil and salt. Let sauce marinate for 2 to 24 hours to blend flavors; stir in parsley.

Preheat grill until very hot, about 550 F. Grill mackerel, skin-side down, until flesh turns opaque and skin blisters. Be careful not to burn the skin. Remove from grill and slice each fillet with a bias cut into two equal parts.

To serve, arrange 2 pieces cut fish on each plate; spoon about ¼ cup agrodolce over each.