I'm on the hunt for a cooking resource (website, app, or book) that focuses on individual ingredients, rather than full recipes. Something where I can just type in / look up the thing I have (filet of salmon, beets, whatever) and get instructions on different cooking methods for that food. For example, right now I have some brussels sprouts and I would like instructions on how to roast them (prep steps, how long, what temperature, seasoning tips), but I don't need or want a recipe for a full meal (e.g. a chicken entree with brussels sprouts on the side). Googling kind of works but the results are hit and miss — I thought there might be a more vetted resource out there. I am happy to pay for this. Any ideas? 
There are many different types of cookbooks, beyond the recipe collections which dominate the market, so maybe there are some guides of this type (like Willeke, I have seen books which contain such information, although I don't recall one where it was the main content). But there is no specialized term for them, so I don't think you can do any kind of focused search for them. One reason for the rarity is that this information is usually learned the other way round. Learning the skill of cooking is, in large parts, learning techniques for preparing food. So people (especially in professional schools) tend to learn technique-by-technique. And part of the knowledge about a technique is also the knowledge about the food categories for which it is applicable. For example, when you learn how to make starch-based puddings, you will ideally also learn that the pudding technique works with any kind of ground grains, but does not work with other kinds of food. Since there is a rather limited list of techniques that are in common use, you end up with a list of techniques in your head, and the knowledge what kind of food can they be used on, and the recognition in the other direction happens more or less automatically. So, in your example, a chef would look at brussels sprouts, and if wondering what to do with them, a list of good options will come up spontaneously. It probably won't be a full list of all suitable techniques known to the chef, that's why creativity is prized among chefs; but it is pretty sure that no unsuitable options will present themselves. If the chef selects "roasting" from this mental list, then there will be no need for them to look up a recipe - they already know how to roast vegetables in general, so they will go on and roast the brussels sprouts. So, in the long-term, you will best improve your skills by learning techniques one-by-one. It is a gradual process, so at the beginning, you easily supplement it with exactly what you have been doing, looking up individual recipes. If you trust books more than random Internet hits (which is not a bad heuristic in itself), then just get yourself a few books specialized in the directions in which you are likely to want to cook, and have fun exploring them. 