A sibling comment mentioned "Salt, Fat, Acid, Heat" by Samin Nosrat.

I cannot praise this book highly enough. If you enjoy food but don't know the fundamentals of cooking, it may actually change your life. Part 1 alone took me from "I need a recipe to make anything other than grilled cheese" to "I can go to a farmer's market, see some ingredients I like, and make something delicious with it".

She explains in great detail the "why" of flavor combinations, balance, different cooking techniques, when and how to season, and is full of obvious-once-you-read-it advice like using the right kind of fat and acid for the cuisine you're making. (e.g. olive oil and red wine vinegar: perfect for Italian dishes, totally out of place in a Thai stir fry — you want vegetable oil and lime juice)

I do sometimes search for recipes to get a vague idea of what proportions make sense, but I don't feel lost without them anymore.

Tangential thought.

Olive oil has been in Italy for a long time, you can make it manually and I guess the high quality stuff sold in nice stores is roughly equivalent to making it manually in terms of final product (maybe not as fresh or whatever but close).

Vegetable oil though… modern vegetable oil is generally very processed AFAIK, and it’s not at all like what Asians would have used to cook with before industrialization when most cuisines developed I think?

I wonder what sort of fat would be used, like, classically, in Thai cuisine? Still vegetable oil?

Possibly coconut oil or other nut oils, if it was possible to press it manually prior to industrialisation. If not then animal fats like lard and tallow.

Good point, those are both very common in tropical Asia. Also palm oil. I was mentally putting all of those in the 'vegetable' category.

That book absolutely changed my life for the better. I went from basically never cooking before (but loving food) to what’s turned into a years-long cooking and baking obsession.

Can’t recommend it enough!

You might enjoy https://www.seriouseats.com or The Food Lab by J. Kenji López-Alt.

Harold McGee’s On Food and Cooking is the classic in the genre of explaining how cooking works. Rather dry textbook style.

I believe Salt, Fat, Acid, Heat is such a book for layfolk like us.

Otherwise proper chef-ing textbooks. I used to work with a former chef and the details she could go into about why/how various processes work in cooking – wow. I learned something new every time we chatted.

You would love Cooks Illustrated, then.

+1 on cook’s illustrated. I love how it goes into the why and also describes the process on how the recipe was formed.