Cooking in the cold winter and out of a core ingredient for a dish? Substitute what you've got in your fridge and cupboard with what the recipe requires. Here is an example as suggested by weblog Gothamist:
1 teaspoon baking powder = 1/4 teaspoon baking soda + ½ teaspoon cream of tartar
You might not come out with the real thing, but you'll certainly come close to it without the extra trek to the grocery store. Can you think of any other recipe substitutions? Share your favourites in the comments.