This post contains an interesting phrase concerning the history of cooking, namely “torn basil leaves”.
There are many ‘rules’ in cooking which have no scientific basis but are just the reflection of past practice. Some of those cooks to the aristocracy who produced books in the Victorian era or earlier merely wrote down what they did and somehow their statements became rules. I’m thinking of Eliza Acton, Mrs Beaton etc.
Here are some of the rules that are not science based:
1. When making mayonnaise, drip the oil in slowly. Mayonnaise and the like separate due to temperature differences between the egg and the oil. So all you have to do is take them out 30 mins before you make the sauce. Wallop it in, no dripping. You can actually use the whole egg if you want, no need to use yolk only.
2. Tear basil leaves, don’t cut them. This arose because some noble told his cook he preferred torn leaves. No culinary purpose to it.
3. Seal your meat by applying high heat for a while. No sealing actually takes place. Browning improves the taste but not the juiciness.
4. For White sauce add the milk to the roux slowly to avoid lumps. No it doesn’t. Lumps are caused by not cooking out the roux sufficiently to burst the flour grains. Cook out the roux and dump all your cold milk in at once. Stir, No lumps, magic.
There are others but I can’t remember them now.