GRILLED WHOLE MACKEREL WITH LEMON, OREGANO, AND OLIVES

Steps:

• Whisk together zest, lemon juice, and salt and pepper to taste, then add olive oil in a stream, whisking until combined well. Whisk in olives and chopped oregano.
• Make 1-inch-long slits at 2-inch intervals down middle of fish on both sides with a sharp paring knife, then brush fish all over with vegetable oil and season with salt and pepper. Season fish cavity with salt and pepper, then evenly distribute 3 lemon rounds and 3 oregano sprigs in cavity. Close cavity, then evenly arrange remaining 3 lemon rounds and 3 oregano sprigs on top of fish and tie fish closed with string at 2-inch intervals, securing lemon slices and oregano sprigs to fish.
• Prepare grill for cooking. If using a charcoal grill, open vents on bottom of grill, then light charcoal. Charcoal fire is medium-hot when you can hold your hand 5 inches above rack for 3 to 4 seconds. If using a gas grill, preheat burners on high, covered, 10 minutes, then reduce heat to moderate.
• Grill fish on lightly oiled grill rack, covered only if using gas grill, 15 minutes. Turn fish over using a metal spatula and tongs, then grill until just cooked through, about 15 minutes more.
• Transfer fish to a large platter using 2 metal spatulas, then cut and discard string. Serve fish with sauce.