Gluten free baking powder is quick and easy to make and costs less than buying a commercial brand. Just make sure you buy cornflour made from maize rather than the finely milled wheat variety that masquerades as cornflour (don’t get me started on labeling laws!).
1 teaspoon baking soda (bi-carb)
2 teaspoons cream of tartar
1 teaspoon cornflour (corn starch – make sure it’s 100% maize)
Mix together and store in a sealed container in the pantry. Shake before use.
Easy!

but if you are concerned about GM and aluminium anti-caking agents, you are still better off sticking to Bob’s Red Mill as its the only one i’ve found that contains neither…
Thanks Corrine. Luckily we have access to cream of tartar, cornflour and bi-carb from our local market that are free of those nasties.