The vectors I have in mind could include (or perhaps be inferred from) recipe text, but they may also include things like nutritional content and corresponding freshest-in-kitchen-ingredients (maybe an ingredient x time-since-purchase vector?) to nearest-match-recipes.

The examples are helpful and well documented, thank you. I'd mention that I'm constraining the technology options to self-hostable and FLOSS software, and with a strong bias towards concepts that are already well-understood by most software engineers, but I'll keep a look out for Pinecone.