1. Preheat oven to 350 degrees Fahrenheit.
2. Roast the garlic by cutting off half an inch from the top of the head and placing the garlic upright in a pan. Pour olive oil over the open garlic and roast uncovered for about 15 to 20 minutes, until tender.
3. Meanwhile, place all ingredients for the dressing in a blender and blend until smooth. Once garlic has cooled, squeeze out the garlic from the papery skin and blend well with the rest of the ingredients. Refrigerate.
Notes: To save time, you can bake the head of garlic and the challah cubes in the same oven at the same time. Roasting the garlic mellows the flavor and takes away the sharp aftertaste that is usually associated with garlic dressing. You can, however, replace the roasted head of garlic with 4 to 5 cloves of fresh garlic, minced.