You turn the hob right down, put the lid on, and go and do something else for an hour. When you come back and stir, there’s a brown layer welded to the bottom of the pan, and depending on how bad it is, a slightly burnt taste running through the whole stew. Autumn is peak season for this.
Why it happens even on low
The lowest setting on a lot of gas hobs is still fairly fierce, and the flame hits a small circle in the middle of the pan. That spot gets much hotter than the rest. Thick things like stews, chilli, porridge, rice pudding and tomato sauces don’t move around much on their own, so whatever is sitting over the hot spot just keeps cooking until it catches. Thin pans make it worse because there’s nothing to spread the heat out.
You can stir every ten minutes, or you can buy a heavier pan. Or you can put something between the flame and the pan that does the spreading for you.
What a heat diffuser does
A diffuser is a flat plate that sits on the burner, with your pan on top. It soaks up the flame’s heat and passes it on more evenly across its whole surface, so the middle of the pan isn’t being blasted while the edges stay cool. It also takes the edge off a burner that won’t go as low as you’d like.
The Ilsa Cast Iron Heat Diffuser is a classic version: an 8.25 inch disc of heavy enamelled cast iron with a hole in the middle, raised ridges on top, and a removable stainless steel handle so you can move it off the hob. Ilsa sell it for gas stoves, say it works with most burners and all sorts of cookware from stainless steel to ceramic, and pitch it as a way to cut down how often you need to stir.
Before you put one on the hob
It’s slow to respond. Cast iron takes a while to heat up and a while to cool down. Give it a few minutes before the pan goes on, and don’t expect the pan to calm down the moment you turn the gas off.
It gets very hot. The handle comes off for a reason. Use an oven glove to move it, and let it cool on the hob rather than putting it on the worktop.
Cleaning is a wipe. It isn’t dishwasher safe. Once it’s cold, a wipe down is all it needs.
It isn’t for searing. It’s there for gentle cooking. If you want to brown meat first, do that straight on the flame, then slide the diffuser underneath for the long simmer.
It’s also handy for keeping a moka pot or a small milk pan from scorching on a burner that’s too big for it. If you cook on gas and keep scraping a crust off the bottom of the stew pot, the Ilsa diffuser is listed on Amazon here, and it’ll probably outlast the pan.
