Place all of the ingredients into a container that can be closed with a lid. Shut the lid and shake well. You could also use a whisk to mix it up.
If you have leftover flour or made extra, store it in an airtight container in the refrigerator.
Story Behind this Recipe
As commercial gluten-free mix is expensive, I researched various recipes on the internet and settled with this. I sometimes use a blender to make this.
Make sure to mix it together very well. If you have this on hand, you can quickly make waffles, brownies, etc. It's very convenient. You can switch the cornstarch with katakuriko but the texture will be different.