There's a farmers market here in Zurich where some Italians drive up and sell Italian products like cheeses, sausages, etc. but one thing I buy from them I've never seen anywhere else - they are rotten salted anchovies packed with peppercorns. Stink super bad and are falling apart but when you're making a sauce you drop one in and the anchovy dissolves and delivers tons of umami - glutamates - and you no longer smell…
also, as you said chefs must know about this:
> Garum remains of interest to food historians and chefs, and has been reintroduced into modern food preparation.