First, peel the Jerusalem artichokes and then cut them into smaller squares (mine were about 2.0 x 1.5 x 1.5 centimeters). I think you can cut them even smaller, perhaps into 1-centimeter cubes. I haven’t tried it myself yet, but I think it will make them even more delicate.
Put sugar, apple cider vinegar, salt, and the whole thyme sprigs in a pot and bring it to a boil.
Add the Jerusalem artichokes when it boils, and let them cook for 2 minutes.
Pour everything into a sterilized jar.
Immediately put the lid on.
Let it sit in the refrigerator, preferably for a couple of hours. After that, they are ready. They are also still really delicious the next day!