If flour is out (celiacs, I see you), cornstarch is your new best friend. The ratio is simpler: use half the amount of cornstarch compared to flour. So, for every cup of soup needing thickening, whisk a tablespoon of cornstarch with two tablespoons of cold water.
Here’s the golden rule: Do not boil a cornstarch-thickened soup for ages. It will break, and you’ll get sad, watery soup again. Bring it to a gentle simmer, watch it thicken, then immediately turn off the heat. It’s like a magical timer—boop, it’s done.
But Wait—What About Tapioca or Arrowroot?
Oh, you fancy! Tapioca starch (from that pudding you love) and arrowroot are great for glossy, clear soups. Use the same cornstarch ratio, but never, ever mix them with dairy directly—they’ll turn into a weird, snotty blob. Mix them with cold water first, then stir into hot broth. Dairy goes in at the very end.
