The recipe thing would probably work along side the Cooking Industry building. The way I imagine it is that once you reach a certain town level you unlock some kind of imbuing station where you arrange the ingredients on a grid, like a wall of item frames, to the recipe and resulting item you desire. Then there would be a command you do to activate the recipe, making your official town dish. One recipe that I think would be really cool would be blood soup, where you use blood and meat and, well, make soup with the beet root soup item representing it.
I don't like the idea of connecting the recipes to Conquest. Territory boarders are constantly shifting. One day you harbour land in the Sunset Isles, but the next an enemy destroys your tgens, cutting off your resources. The items you should be aloud to make these custom recipes from should be found within the immediate range of your town, not the entire radius of the territory, if your town even has any.