Traders probably won't buy stew forever
This, of course, could change if a trading overhaul (which I haven't looked to see if specifically mentioned, but might fit into the World Economy chatting that I've seen) makes it so that traders actually reduce the premium on your most prolific goods (whether that be mugs or stew or mechanisms). As a modifier like the "requested goods" going for ~200%, but for 75%, 50% or whatever.
So, flood the market and, unless the 'next civilisation on' in the trading circuit[1] has a continuing requirement for tallow biscuits, bone bolts or caged kittens, you get less return on them. To the extent that the value dips to trivial amounts unless you moderate it, perhaps switching to idols, instruments, or whatever to keep things fresh, but still able to flood the market with various non-perishable/non-comsunamle goods, at least, in the long-term.
[1] Noting that a proper economy must have traders actually following a circuitous/reciprocating trade-route, behind the scenes, and their attitudes to goods being bought and sold at your stop being affected by the requirements at stops they make preceding and following yours. Or a reasonable facsimile of such behind-the-scenes processing based upon a bit of memory. And as traders cannot, unlike Santa Claus, be everywhere in the world (or area) at once during the same autumnal trading period, and the route may adjust anyway as mountainhomes and human/elven settlements are added and removed from their roaming itinary (for various reasons), it wouldn't be quite the same as now...