Prepare grill for cooking. If using a charcoal grill, open vents on bottom of grill, then light charcoal. Charcoal fire is hot when you can hold your hand 5 inches above rack for 1 to 2 seconds. If using a gas grill, preheat burners on high, covered, 10 minutes, then reduce heat to moderately high.
Lay bell peppers on their sides on lightly oiled grill rack and roast, turning occasionally with tongs, until skins are blackened, 10 to 12 minutes.
Transfer to a bowl, then cover and let steam 10 minutes. Peel and seed peppers (reserving juices), then cut into 1/4-inch-thick strips.
Stir together peppers (with their juices), garlic, oil, vinegar, oregano, sea salt, and pepper and marinate 30 minutes at room temperature.
•If your sea salt is very granular and pebblelike, crush it using the flat side of a large heavy knife or the bottom of a heavy skillet.•If you're unable to grill outdoors, peppers can be broiled on rack of a broiler pan about 2 inches from heat 10 to 20 minutes.•Peppers can be roasted and cut into strips (but not marinated) 2 days ahead and chilled, covered.
