Gather the ingredients.
Cut away the peel, being sure to remove any woody or stringy parts, just under the surface. If the bulb is young, you will not have to cut as deep as if it is old. If your kohlrabi is fresh, save some of the inner, tender leaves for garnish.Note: The younger the kohlrabi is, the better. Older vegetables become woody and very pungent. If you do have a large one, you will not need as many, but you may have to remove more of the peel.
Cut the bulb into thick slices with a large knife, then into strips or cubes, as you like.
Heat the vegetable broth or salted water to boiling, then add the kohlrabi, reduce the heat and cook the vegetables until soft, 5 to 10 minutes. Drain, reserving broth, and set aside.
Melt butter in a pan and stir in the flour. For a gluten-free sauce, use gluten-free flour, such as rice flour, brown rice flour or sorghum flour, all of which thicken just fine.
Cook the flour in the butter over medium heat for several minutes, stirring constantly.
Little by little add the saved broth or cooking water. Stir after each addition until smooth, then bring it back to bubbling. Add enough of the broth to make a velvety sauce, about 1 to 2 cups.
Season to taste with freshly grated nutmeg and salt.
Stir in the cooked kohlrabi and heat through.
Chop the reserved leaves and some parsley and sprinkle on top of the vegetables for a little color and a nice presentation.