Kimchi is a lot like sauerkraut. Both start with cabbage (or whatever) and salt, and ferment the cabbage through lactic fermentation. Kimchi generally goes in the fridge to slow the fermentation after a few days, with older kimchi being reserved for cooking rather than eating raw; sauerkraut is fermented for weeks. Kimchi is usually seasoned more heavily than sauerkraut, although not always.
Once in a blue moon you see fennel sauerkraut on a restaurant menu - or in your grandmother's house, I don't know - and I thought, well, how about fennel kimchi instead. I actually left out most of the kimchi seasonings, though, using only salt, sugar, and Korean red pepper flakes - the idea was to get a lactic-fermented fennel, slightly spicy, that would work with anything you'd usually pair fennel with, and so I didn't want too much in the way of garlic, ginger, or seafood.
Thus tonight, fennel kimchi pizza: