One thing you can try to increase the fluffiness of your pancakes is to separate the egg whites from the yolks so that you can incorporate more air into the batter. Gently combine all off the ingredients except the whites, whip the whites to stiff peaks, and then gently fold the whites into the rest of the batter.
Yes, I have found several sources that say that citric acid is about 4 times the strength of cream of tartar. So, mix 1 teaspoon of baking soda and 1/2 teaspoon of citric acid and use a 1/2 teaspoon of the mixture.
That should work. Let us know!
EDIT: Oops, I should have mentioned this before the OP accepted. Hopefully, he'll realize, or see this. That substitution will approximate single action baking powder, so don't dilly-dally before cooking! (Difference Between Double and Single Action Baking Powder)
2nd EDIT: Just to be extra confident, I compared the reaction (according to the method of David Lebovitz) of 1/4 tsp of my recommended mixture with boiling water and 1/2 tsp of new Rumford Baking Powder with boiling water. The results seemed identical.
3rd EDIT: I actually found this question pretty intriguing. While I could find plenty of evidence that it should work (including my own little water experiment), I couldn't find anything definitive that said it does work.
Well, it just so happens that I had some cream in the fridge, and I have been meaning to try America's Test Kitchen's cream biscuits. With nothing in them but flour, sugar, baking powder, salt and cream; they should be perfect for comparing real baking powder with the substitution.
SO:
I made biscuits.
They taste as identical as they look. (pretty yummy too)
I can now say with authority, the substitution works. 1 tsp fresh Rumford Brand Baking Powder = 1/2 tsp of a mixture of 1 tsp baking soda and 1/2 tsp citric acid.
Best Answer
Baking powder contains baking soda, plus acidic ingredient(s).
If you have cream of tartar, you can make baking powder directly:
Without cream of tartar, you can substitute baking soda for baking powder as long as you have an acid in your recipe, like buttermilk. If your recipe does not contain an acid, you should add one or the baking soda will remain inert. Based on the above proportions, you should be able to substitute 1/2 tsp baking soda + acid for 2 tsp baking powder.
For pancakes specifically, if you rest your batter, you should fold in the baking soda at the end so you do not lose all the leavening action.