What is a Poolish? A poolish is called a preferment - it is similar to a sourdough starter, but uses commercial yeast, instead of airbourne yeasts. It also doesn’t require any feeding, unlike a sourdough starter A poolish will build flavour and create crispiness in pizza, bread & and pastries. It uses equal parts flour and water and a tiny bit of yeast. It should mature at room temp for around 18 hours. It needs to, at least, double in size. Always use a glass vessel to make your poolish - mark