Kohlrabi should be no larger than a tennis ball, they tend to get woody, and hard the larger they are. The leaves can be used along with the base. Weather green or purple they need to be peeled and both varieties have a cream colored inside. As you might imagine from its name, both raw and cooked kohlrabi has a sweet cabbage flavor with a crisp toothsome turnip like bite.
On one occasion this week I simply diced the kohlrabi, blanched it, then sautéed it with English peas, and braised pork belly. Secondly, and in a way to maximize the flavor of the kohlrabi I made a slaw with raw kohlrabi that was shredded, a chifinade of the kohlrabi leaves, some onion, and a dressing that included a bit of ginger for spice, and caraway seeds. One very pleasant surprise about raw kohlrabi is that it doesn't oxidize, or turn brown once cut.
Salsify has something of a fleeting history and definition. What is commonly called Black Salsify in the American market has a colorful variety of names including; Spanish salsify, also known as black oyster plant, serpent root, donkey dick, viper's herb, viper's grass and that's only the beginning. A closely related genus of plants is also called ‘salsify’ and generally includes anything which we would consider a 'wild flower' of which the small roots and young shoots are edible.
So, enough of the confusion. Black Salsify originates from southeastern Europe, but by 1600 was grown through Europe cherished for its hardiness in cooler climates. This salify plant has a taproot that can grow up to a meter long, but most available are about a foot long and one inch diameter. They have a dark brown skin that needs to be peeled revealing an astonishingly ivory white inside. Unfortunately peeled salsify quickly oxidizes so if a white product is desired the peeled root should be submerged in acidulated water. Salsify is described as having the flavor of oyster, but I don't taste it. I get a rather earthy, sweet, nutty flavor that reminds me more of artichoke and potato skin.
Salsify is commonly turned into a soup, which is nice. I like to caramelize batons of salsify in butter and serve them as a starch. I've also used them raw, cut very thinly and marinated with sherry vinegar and a touch of vanilla. This week I made salsify-potato latke. I used about twice as much salsify as potato, an egg, a touch of flower, some nutmeg and sautéed them in butter. They came out very nice, the nutty flavor came through nicely and there was a perfect amount of starch to hold things together.