Fran Lebowitz is credited with the definitive description of the pitfall of cold soup. “More often than not the dinner guest is left with the impression that had he only come a little earlier he could have gotten it while it was still hot.”
There are a couple of reasons for this. One, quite simply, is tradition. We do not normally picture soup as cold. As a result it has to stand out in some fashion — to be RIGHT when cold.
The second largest problem is the nose. See, a LOT of flavor from eating actually comes from the smell. Steam carries odors. As a result most cold soups come across as rather bland.
And finally there’s a simple fact that your taste buds are more effective when dealing with warm food.
Look, the sad thing is that every vichyssoise I’ve ever eaten tasted better if I could warm it. I know it’s a classic and it’s daring and it’s a real challenge to balance the subtle flavors so none overwhelm the dish, and oh by the way to get the texture so smooth. But every single one I’ve tried that I’ve been able to take to the microwave or warmer tasted better. And those that had just a touch of coarseness or weren’t /quite/ perfect? Heating took care of it. I think our tongues, lacking taste, seek SOMETHING in compensation and so we get the texture issue. But that is just a guess.
So let’s take a look at what this means. A cold soup has to be pretty — in fact it should look like its cold condition is right. A cold soup needs to be very flavorful. And it helps if you can do something to carry some nose. Oh, yes, and the soup still has to fulfill the role, be that appetizer or palate cleanser or light meal (alone or paired with, say, sandwiches).
Oh, one last thing (though it’s personal taste). I like my guests to realize it’s a soup, not a fruit or veggie juice served in a bowl. That works, by the way, but why not just serve it in a glass? The tricks are usually to have it a bit thicker or to have ‘chunks’ — bite sized pieces of something.
Now take a moment and go through your cookbooks, looking at cold soups. You’ll begin to see why some of the choices are made. There’s a heavy hand with spices. Veggies and fruits and herbs are pureed, but there’s so much it makes it thick. Many of your recipes will add a bit of vinegar or wine or other alcohol so the evaporating fluid will carry odors to the nose.
Look, let’s go with a very easy recipe just to give an example. Let’s use a cucumber-mint soup.
You’re going to need four large cucumbers, a large handful of mint, a cup of chicken broth, a cup of half and half or light cream, a single sprig of dill leaf, a bit of salt, and a tablespoon of sugar. Oh, and you will want a quarter cup of sweet white wine (or champagne that’s gone flat).
Now the first thing you’re going to do is reduce the chicken broth down to between 1/4 and 1/3. It’s going to thicken, and it’s going to concentrate the taste. Once that’s done, let it cool.
Peel and rough chop 3 of the cucumbers. The last one should be cut into 1/3 inch dices — if you’re going casual, just rough chop them as well — but reserve this portion however you chop it.
Now, you’re going to use a blender to puree almost everything. Save the reserved cucumber, enough mint to sprinkle leaves as a garnish on the bowls, and the champagne/wine. Other than that, work in small batches and get it all blended. For me, it works if I pour in a third of everything, puree, pour into my bowl and do the next third, repeat.
Anyway, once it’s all blended, whisk it to mix the batches, taste it and tweak the seasoning if you need. Put everything – the soup, the reserved cucumber, mint, and wine – into the refrigerator for a couple of hours. Just before serving, whisk in the wine and stir in diced cucumber. Ladle into bowls (getting a bit of the cucumber), and top with that garnish of mint
Cucumber, by the way, works cold and doesn’t seem to be as good warm. This reinforces the psychology that this is a COLD dish. The thickness from the puree and the light cream reinforce the soup vs juice meme. There’s a LOT of mint in this but it’s not really overwhelming. And the little bit of wine will not only bring its taste but its alcohol will lift the cucumber and mint to the nose while eating. The chicken broth? More flavor, and one more subliminal cue that this is a soup. It’s reduced so the soup stays relatively thick.
Psychology, tongue, and nose are the key to making the person eating the cold soup know it’s not that they were too late to get it warm.