How to specify what something is made from/of

Question

As I understand it, a wooden plank is "une planche DE bois" because it is made entierly from wood, while a tomato soup is "une soupe À LA tomate" because it has other ingredients as well.
But in the most recent writing challenge we had "et comme plat principal, j’aimerais la salade DE chèvre chaud".     Surely, a salad has several ingredients, so why is it not  ".. salade AU chèvre chaud" ?

Accepted Answer

Bonjour Joakim !

Very interesting point! I would have described the difference between "de" and "à la" in a slightly different way: when "de" definitely expresses what something is "made of", I would say that "à la, au..." are more about "flavour", what are the main ingredients or the main "flavours" of something.
Have a look at our related lesson:
Compound nouns formed with prepositions à/de/en in French

However, I must admit that I'm quite stuck in the case of "salade de chèvre chaud"...
I've therefore looked into it, and foudn out that while it is definitely the colloquial way to say this, some people also say "salade au chèvre chaud" in French!
So I guess it's a question of point of view here, and both formulations are acceptable, though I'd never heard "au chèvre chaud" myself until today :)
I'll add that option to the Writing Challenge.

Merci beaucoup et à bientôt !