Incorporate Egg Yolk For Thicker, Creamy Soups
Not only are eggs delicious and versatile, but they're also an all-purpose cooking aid that enhances or otherwise facilitates the assembly and execution of countless dishes. Apart from taking center stage in the likes of omelets, scrambles, and soufflés, eggs also help baked goods rise, are key binding agents, and create decadently creamy sauces. They can make excellent thickening agents for soups, too.
Some chefs argue that you should incorporate an egg yolk into any dishes that you want to thicken. Egg yolks contain all of the flavorful fat and creaminess responsible for the richness and consistency of myriad sauces from mayonnaise to hollandaise. Italians use a simple egg yolk and some parmesan cheese to transform a plate of spaghetti into the famously decadent pasta carbonara.
The beauty of egg yolks as a thickener for soups is that they also offer an inimitable richness that other thickening agents like potatoes, corn starch, and flour lack. Eggs are household staples that will enrich your soup with valuable nutrients. They're also a low-carb and dairy-free alternative to flours, roux, and starches. Since eggs are also well-known emulsifiers, they effortlessly blend with most liquid ingredients, making them fit to thicken cream, roux, and broth-based soups.
How to incorporate egg yolk into soup
While you might not have heard of using egg yolk as a soup thickener, it's a common practice in Greece. Tempering egg yolks with hot broth is a key step in making the Greek chicken soup Avgolemono.
Using Avgolemono as your guide, you can incorporate egg yolk into any soup, though you'll more commonly incorporate the yolk at the tail end of the cooking process rather than near the beginning. Temperature is an important factor when adding egg yolks because boiling or simmering liquid will curdle the eggs and ruin your soup (unless you're making Chinese egg-drop soup).
Once you've fully cooked your soup, ladle some out of the pot and turn off the stove. Then, add the reserved liquid in a slow drizzle to the egg yolk and whisk to combine. Once you have fully blended the egg yolk, you will add the mixture back into the hot soup and stir. The soup must not be boiling or simmering while you whisk the eggs into the soup.
For an even thicker soup, you could use heavy cream with your egg yolks instead of reserved broth or liquid from the soup. This would make an ultra-indulgent addition to cream of mushroom soup, corn chowder, or tomato basil bisque.