This section is from the book "A Book Of Recipes For The Cooking School", by Carrie Alberta Lyford. Also available from Amazon: A book of recipes for the cooking school.
Kohl-rabi should be used when young and tender, while the leaves are not more than 2 or 3 inches in diameter. The leaves are used as greens, but the root is the better part.
Wash and pare the kohl-rabi, then cut in thin slices. Put into salted, boiling water and boil, with the cover partially off the saucepan, until the vegetable is tender. This will take from 30 to 50 minutes. Pour off the water and season with butter, salt and pepper.
Kohl-rabi may be boiled with pork in the same way as kale. The cold boiled vegetable may be served as a salad.