Around the seed cavity of a quince is a hard core of flesh that tends to stay hard after cooking. When a recipe requires coring a quince, you’ll want to remove all of this hard flesh. Doing so can be difficult; a sturdy paring knife will suffice, but only if looks don’t matter much. After accidentally cutting crosswise through a few quince slices, you may find yourself hunting through your Drawer of Useful Things (as I call mine) for a more appropriate tool.
Forget the pear corer; it’s too flimsy. What you need is the tool pictured here, a pointed spoon with sharpened sides. Best known as a peach pitter or pitting spoon, it’s designed for jabbing into a stone fruit and withdrawing the pit while leaving the fruit intact. You can also use it for scraping the pith from a citrus rind, cleaning the cavity of a winter squash, and taking the choke out of an artichoke.
My mother-in-law probably thought I knew what a peach pitter was when she bought me mine, at least a dozen years ago, but I didn’t, and in fact I’ve never tried to pit a peach while leaving it whole. I mainly use my pitting spoon for coring apples and, especially, quinces.
I don’t know where my mother-in-law bought my pitting spoon, and finding one today can be difficult. Canneries, once the main market, now use big machines instead. But here are two U. S. sources: Kitchen Conservatory and Biggest Little Kitchen Store.
If you have no pitting spoon and want to use a paring knife instead, the safest way is to lay the quince slice cut-side down on the cutting board and make two cuts, starting on either side of the core and meeting in the middle behind it.