Most of the time the particular character of a wine is lost in cooking: The basic structure and body may remain, but any finesse and identity are lost. Strangely, however, when fine wines are sweetened with sugar syrup, the character of the wine emerges in such a way that it’s easy to identify the varietal and even the region. Alsatian Riesling is a good choice for this foam because of its strong varietal character and its high acidity; the high acidity allows the addition of more sugar, which stabilizes the spoom.

This recipe uses a vacuum method in which the spoom expands considerably. Unlike the usual method of applying vacuum to a liquid in an Erlenmeyer flask, a spoom or other foam requires a vessel you can ultimately reach into with a spoon to serve. You'll need a large jar or beaker (at least 1½ quarts/1.5 liters), with a tight-fitting stopper; the stopper should have a hole in the middle with a tight-fitting 6-inch (9 centimeter) piece of glass tubing to connect with the vacuum pump, usually via rubber tubing. This may require an adapter. If you don’t have a setup for vacuum, prepare the spoom in the same way and just leave out the vacuum step and freeze the mixture in a bowl. The spoom won’t be as impressively foamy, but it will be as delicious.