The Soup Thickening Trick All Bread Lovers Should Know About

The sourdough realm comes with its own subset of scientific vocabulary terms like "autolyse," "amylase," and "banneton." Today, we're focusing on one such word in the sourdough lexicon — discard — and how it can take your homemade soups to thick new levels. It may be called "discard," but there's no need to literally throw that liquid-gold-ingredient into the trash. Put your sourdough discard to thrifty, good use and use it to thicken your soups. 

If you've never made sourdough bread before, sourdough starters need to be "fed" as part of regular maintenance. "Feeding" is when you add fresh flour and water to the growing starter, and to make room for these new additions, a few scoops of the existing starter must be removed. This removed portion is the discard.

Sourdough discard is made of flour, water, and healthy microorganisms, primarily wild yeast and lactic acid bacteria. As such, it can be functionally used like a roux or cornstarch slurry with the added benefit of greater nutritional value. Discard also has a creamy, thick liquid texture, not unlike ranch salad dressing.This facilitates easy inclusion when stirred into a batch of soup, and the discard's naturally pungent, pleasantly sour aroma can bring instant dimensionality to milder, one-note soups. In fact, Polish sour Żurek soup is made using fermented rye sourdough starter, and fermented cereals feature prominently in many other traditional, hearty Eastern European soup recipes. 

To thicken your homemade soups with sourdough discard, ladle a cup of hot soup from the pot into a glass measuring cup or dish. Then, stir in a few spoonfuls of discard. The warm broth will aid in even, homogenous mixing. From there, just stir the mixture back into the main soup pot. Repeat as necessary, adding more sourdough discard until the soup is as thick as desired. Just keep in mind that the soup will continue to thicken as it cooks down. 

Be sure to add the discard to the soup pot early enough to allow adequate time for the discard to cook fully (no one wants to bite into raw discard). If you don't happen to be making soup at the same time as feeding your sourdough starter, that skimmed discard can be stored in an airtight container to use at a later date; in the fridge, it'll last for a few weeks.

Discard can be used to thicken any soup that might benefit from a slurry. Acidic tomato bisque or mild vichyssoise would doubly benefit from the sour tasting note. Or, you could lean sour-savory with the flavor profile by stirring discard into umami-rich cream of mushroom soup or this silky pureed carrot apple soup with ginger, celery, thyme, and sage. You could even use discard to make a pungent take on Panera's classic broccoli cheddar soup in a bread bowl. Emulate and elevate the existing dream-duo with a tangier twist.