How to Make It
Pat fish dry, inside and out, with paper towels. Place fish on a wire rack set inside a rimmed baking sheet. Refrigerate, uncovered, until skin is dry, at least 8 hours or up to 2 days.
Open bottom vent of a charcoal grill completely. Light charcoal chimney starter filled with briquettes. (Never use charcoal lighter fluid to start a charcoal fire; it will give grilled foods a chemical taste.) When briquettes are covered with gray ash, pour them onto bottom grate of grill. Insert top grill grate, and cover grill. Bring temperature to medium-high (400°F to 450°F) by adjusting top and bottom air vents.
Place bell peppers on oiled grates over hottest part of the grill; grill, uncovered, turning occasionally, until charred all over, 8 to 10 minutes. Transfer bell peppers to a medium bowl, and cover tightly with plastic wrap; let stand 10 minutes. Using a paper towel, scrape off skins from peppers; discard skins. Slice peppers lengthwise into 1/3-inch-thick strips; remove and discard seeds and core.
Place cherries on oiled grill grates, or use a grilling basket or an 8-inch cast-iron skillet. If using a skillet, preheat it on the side of the grill while peppers are cooking. Grill cherries, uncovered, turning or tossing occasionally, until they begin to char and weep, 2 to 4 minutes. Transfer cherries to a medium bowl; let cool 5 minutes. Halve cherries; remove and discard pits.
Stir together bell peppers, cherries, 2 tablespoons olive oil, vinegar, chopped thyme, chopped oregano, 3/4 teaspoon salt, and desired amount of crushed red pepper in a bowl. Set aside to marinate while preparing fish.
If needed, add 10 to 15 charcoal briquettes to grill to bring temperature up to 425°F. Rub outsides of fish evenly with grapeseed oil. Sprinkle outside and inside cavities of fish evenly with remaining 1 tablespoon salt. Stuff 4 oregano sprigs and 4 thyme sprigs into each fish cavity, stem ends first, to lodge them securely. Scrub grill grates clean using a grill brush. Dip a folded-up dish towel into grapeseed oil; hold towel using tongs, and thoroughly grease grill grates. Place fish on grill grates; grill, uncovered, 4 minutes. Using a fish spatula, gently lift up part of each fish to see if the skin is sticking to grates and whether you’ve established a crust. If there’s no crust yet, let fish cook an additional 1 to 2 minutes. Place a spatula in the cavity of each fish, and roll it over; the goal is to touch the fish as little as possible. Even if it sticks a little, turn the fish over, and leave it alone to finish cooking. After 4 or 5 minutes, use a metal skewer to pierce the meat at its thickest point. When removed, it should feel quite warm on your lip. If it is, remove the fish from the grill. For an additional test, fleck a bit of meat off the part that you will serve yourself; fish will flake when it is done.
With tongs in one hand and the spatula in the other, use the tongs to lift the head; slide the spatula under the body, and transfer fish to a serving platter. Drizzle evenly with remaining 2 teaspoons olive oil. Serve with lemon or lime wedges and marinated pepper-cherry mixture.