Substitutions that work, and the ones that will not

Some ingredients are flavour and can be swapped freely. Others are structure, and swapping them changes what you are making.

The useful question is never what tastes similar. It is what job is this ingredient doing.

Flavour is the forgiving category. Herbs, spices, most vegetables, the cut of meat in a stew: change them and you get a different dish that works. Thyme for rosemary, chicken for pork, leeks for onions. Cook what you have.

Structure is where things break. Eggs bind and set and lift. Sugar is not only sweetness, it is moisture, browning and tenderness. Fat is texture. Flour is the frame. Take a third of the sugar out of a cake and you do not get a less sweet cake, you get a smaller, paler, drier one.

Acid is its own case. Lemon juice, vinegar and yoghurt are often interchangeable with each other and almost never with nothing, because in a great many recipes the acid is what stops the dish tasting heavy.

The safe habit is to substitute within a category, one thing at a time, and to write down what you did. A recipe that worked with two changes tells you nothing if you cannot remember which two.

Photograph: Kimberly Vardeman — CC BY 2.0, via Wikimedia Commons