3 bunches large green onions (see Note), or baby leeks
2 tablespoons olive oil
Salt and freshly ground black pepper
2 large limes, cut into wedges
This dish works best with knob onions (overgrown green onions with a bulb about 1-inch across). If these are not available, use the largest green onions you can find so that they don't soften too quickly when grilling.