Peel the onions, cut them in half lengthwise, then into very thin lengthwise slices. Cut the leeks in half lengthwise and wash them well. Cut the leeks into 1/4-inch crosswise slices (the green tops can be saved for stock).
Peel and slice the shallots into thin slices. Place the onions, shallots, and leeks in a heavy pot with 1 cup of water or vegetable stock. Over medium heat, cook the vegetables until the water has evaporated and the vegetables have begun to soften without coloring. At this point add 6 cups of water or vegetable stock and salt and white pepper to taste.
Simmer for 1/2 hour. Remove 2 cups of liquid and vegetables to a
blender or food processor.
Puree well and return the puree to the remaining soup. Cut the garlic clove in half and rub the
bread slices with the cut side of the clove.
Toast under a
broiler. Put 1 slice of
bread into each of 6 bowls, pour the soup over, and garnish with the chives.
