1 lg. onion, unpeeled
1 garlic clove, unpeeled
1 lb. zucchini, cut into 1/2 inch slices
1/2 tsp. salt
4 1/2 c. cauliflower florets, about 1 lb.
2 tbsp. unsalted butter
1 1/2 tbsp. sour cream
1 tsp. sherry wine vinegar
1/4 tsp. freshly ground pepper

Preheat oven to 425 degrees. In a small baking dish, roast the onion and garlic, unpeeled and uncovered, until tender, about 40 minutes for the garlic and 1 hour or slightly longer for the onion. Let cool.

Meanwhile, place the zucchini in a bowl and sprinkle with the salt. Let stand for about 1 hour to draw out the moisture. Pat dry. Steam the cauliflower over high heat, covered, until fork-tender, about 8 minutes. Transfer to a food processor. Steam the zucchini until tender, about 3 minutes. Add to the cauliflower.

In a small skillet, melt the butter over moderately high heat. Cook, watching carefully, until brown, 1 to 2 minutes. Immediately remove from the heat and add to the vegetables in the processor.

Snip off the end of the roasted garlic with a scissors and squeeze out the soft pulp. Add to the food processor. Cut off the stem and root end of the onion and peel off the brown outer skin. Add the onion to the processor. Add the sour cream and vinegar and puree until smooth. Season with the pepper and additional salt to taste. Set aside, covered with a kitchen towel, for up to 3 hours. Reheat in a double boiler before serving. For a special meal, use a pastry tube and flute or scallop.