25/08/2026
On Sunday I boiled 3kg of onions ready for making Tarte in Ymbre Day, a medieval onion tart. Because I hate waste, I saved the cooking water and reduced it down into a rather lovely onion stock.
The boiled onions were drained, cooled and put into the fridge until I had time to deal with them.... Unfortunately Monday loomed with a thumping migraine so said onions were left considerably longer than I had intended π€¨
Fast forward to this morning and I discovered something rather strange lurking at the bottom of the bowl...
**Onion jelly**
Not just slightly thick onion juice, proper, gelatinous, translucent stuff that was quite happily adhering to the side of a tilted bowl and could be picked up on a spatula! Naturally, this meant everything had to stop while I investigated what on earth I'd accidentally made. π
It turns out that cooking onions can release soluble polysaccharides (long chains of carbohydrates) from their cell walls, particularly pectins (the stuff that makes jam wobbly). Leave those cooked onions sitting in the small amount of liquid they continue to release, and apparently you can end up with something remarkably gel-like. Even more interestingly, it's very sweet.
And the tarts? They've come out tasting rather unexpectedly like a mildly onion-flavoured Portuguese custard tart π³ π
Which has obviously led me to wonder what would happen if I added a little more sugar and grated nutmeg to the last bit of filling...
This is why I never get anything done. I start off making medieval onion tarts and somehow end up conducting experiments in onion polysaccharides.
For science! π π¬π§ π§
π₯§π¬π