Rinse an Old-fashioned glass with hot water to warm it. Add the sugar, orange peel, lemon peel, and brandy, and mash with a spoon or muddler. Light brandy and blaze for a few seconds.
This is the type of soup that, at first glance, might seem a little…unexciting. But you’re underestimating the power of mushrooms, which do the heavy lifting.