If you need grain free baking powder, here's Elizabeth's recipe -
Grain-Free Baking Powder
Most commercial baking powders contain a grain-based starch.
Thankfully it’s easy to make your own!
Active Time: 2 minutes
Yield: about 6 tablespoons
¼ cup cream of tartar
2 tablespoons baking soda
1 teaspoon tapioca starch
Whisk the cream of tartar, baking soda, and tapioca starch together in
a small bowl.
Store in the pantry in an airtight container for up to 4 weeks.