Kohl rabi is a traditional vegetable in Norway and I think the rest of Scandinavia, probably because it's one of the few things which will grow willingly up here. It's considered maybe a bit boring and "oldfashioned", but still a staple eaten throughout the country. I love fresh kohl rabi, good ones are sweet and crisp eaten raw, and it's a good veg to have in a stew, or sliced thinly and wok'ed. Aged ones get a bit rubbery though, and bitter sometimes. Mashed kohl rabi, like mashed potatoes, with butter and milk, is very good!