Preparing a recipe that requires you to stir with one hand while slowly and carefully pouring with the other hand? America's Test Kitchen has a unique way to keep that mixing bowl in one place while you work.
Simply grab a tea towel and a saucepan that's a little smaller than the lip of your mixing bowl. Drape the towel over the opening of the saucepan, rest the bowl inside and mix away. The towel/saucepan combination means the bowl won't spin or move away from you while you mix.
Many of us use a towel on its own as a stabilising surface, but this is a neat adaptation that works well.
Best Ways to stabilise a Mixing Bowl [America's Test Kitchen]