I’ve heard that Zùsto gets lumpy when you mix it with butter – is that right?
That can happen. Zùsto is a high-fibre product and fibres such as this are water soluble, but dissolve more slowly than sugar. That is why we recommend using Zùsto first of all with dry ingredients, before adding the wet ingredients. So first add flour, and then butter. Do you want to mix Zùsto directly with butter? If so, it’s important to use butter that is at room temperature. The most common reason why ingredients separate is because of a difference in temperature. You should therefore remove the butter from the fridge several hours in advance, and mix it in a food processor before slowly adding the Zùsto, one spoon at a time. This is how you can prevent lumps from forming.