A couple of weeks ago, I was flipping through one of my vintage cookbooks (In Pursuit of Flavour by Edna Lewis), and I noticed a recipe for baking powder. What? You can make that at home?
So I checked out the ingredients, and yes you can. In fact, it's very, very simple. This knowledge came at a perfect time because my store-bought baking powder was nearly gone, and sure enough, one naptime I wanted to bake something and (re)discovered at the last minute that I didn't have enough baking powder. (My favourite banana bread recipe, which I make once or twice a week, uses 3 teaspoons of the stuff.)
Anyways, I followed the recipe for baking powder, replacing corn starch with tapioca starch. I used my kitchen scale to measure out the weights but I think next time I might not do that. I suspect my 4-pound scale just isn't accurate enough to do 1 or 2 ounces, because while I was measuring, I touched the scale and it suddenly sprang up past the mark I was going for. I decided to pretend I hadn't seen that and just poured it all together.
I've used it several times now, and everything I make seems to rise just fine. I couldn't help but wonder if cream of tartar is some nasty toxin so I looked it up. In case you didn't already know, it is not a toxin. It's the powder left in wine barrels, which comes from tartaric acid. It provides the acid that reacts with the basic baking soda.
So here's the recipe:
2 ounces (1/4 cup) cream of tartar
1 ounce (2 tablespoons) baking soda
1 1/2 ounces (3 tablespoons) starch (corn, potato or tapioca would all work)
Ms. Lewis recommends weighing the ingredients and cautions that if you do use measuring cups and spoons, "use a light hand and do not pack them down." She goes on, "Also, it just isn't true that when you use single-acting baking powder you have to mix up the dry and liquid ingredients quickly and bake them right away or else the batter will die. I make spoon bread batter the night before and it rises just fine the next day."
So that's good to know too.