How to Make It
Set up your smoker or grill for smoking. If using a stovetop smoker, place the sawdust in the bottom and arrange the vegetables on the rack. If using a grill, set it up for indirect grilling and preheat to medium. Toss the wood chips on the coals. Arrange the vegetables on the grate over the drip pan.
Smoke all of the vegetables for 15 minutes—they should be smoked, but not cooked through. Transfer to a platter to cool. Unskewer the scallion whites and garlic and discard the toothpicks.
Cut the smoked vegetables into 1-inch chunks. Place in a food processor and grind to a coarse purée. Work in the olive oil, vinegar and water, adding enough water to obtain a pourable consistency. Correct the seasoning, adding salt, pepper and vinegar if needed to taste.
The gazpacho can be served now, but it will taste even better if you chill it for 1 hour to allow the flavors to blend. Just before serving, correct the seasoning, adding salt or vinegar to taste. Ladle the gazpacho into bowls or martini glasses and sprinkle with the chopped scallion greens. Serve at once.