Here is a simple and delicious way to prepare Kohlrabi. I served this with Teriyaki Salmon (cooked on the grill!) and rice.
Kohlrabi with Garlic, Ginger and Scallions
3 Kohlrabi bulbs, peeled and julienned
1 or 2 cloves garlic, minced
1 inch of ginger, peeled and minced or grated
3 scallions, sliced thinly
1 Tbs soy sauce
1 Tbs rice wine vinegar
1 Tbs peanut oil
Heat skillet with peanut oil until hot. Add Kohlrabi and cook until starting to brown on some edges (about 4-5 minutes). Add the garlic, ginger and scallions. Stir until fragrant (about 1 minute) then add the soy and vinegar. Stir and cook until the liquid is absorbed, about 2-3 more minutes. Enjoy!
Until a few years ago I had never even heard of this vegetable. Then when we were members of a CSA I got a bunch of it and had to figure out what to do with it. One of my favorite cookbooks is World Vegetarian by Madhur Jaffery. She gives great info on every veggie imaginable and I have adapted one of her takes on Kohlrabi.

Asian Kohlrabi
2-3 heads of Kohlrabi
1 Tbs peanut or vegetable/olive oil
1 clove garlic (pressed or finely minced)
salt and pepper
2 tsp soy sauce
1 scallion, cut into 2 inch lengths, then quartered
Peel the kohlrabi and trim off the bottom 1/8-1/4 inch. Slice into 1/4 inch rounds, then stack and slice again into matchsticks.

Heat oil in frying pan. When hot add garlic (I pressed mine), stir once then add kohlrabi. Season with salt and pepper. Stir and reduce meat to med and saute until pieces start to brown and they are tender. Add scallions and soy sauce. Stir and serve.

Noah (10) was surprized at how much he liked it.
Eitan (8) really liked it.
Lilian (5) had to be cajolled into trying it but liked it anyway.
Jethro (2) picked at it.