Springime is fresh bulb onion season, and that's when torpedo onions appear on the market. These pungent, football-shaped onions hail from the Italian town of Tropea, where they were introduced by the Phoenicians more than 2,000 years ago.
Cut the green tops from onions and discard. Remove the outer skin if it's dry or damaged. Trim the stem end, but don't remove it entirely or the onion will fall apart. If your torpedo onions are large, cut them in half lengthwise.
Mix together the olive oil, vinegar, and a sprinkling of salt and freshly ground pepper. Place the onions on a tray or platter and brush liberally with this mixture.
Grill over a low, slow heat so that the onions have a chance to caramelize. Brush with the oil and vinegar mixture once or twice during the grilling process. It will take about 30 to 40 minutes to completely cook the onions. Serve warm.