Set oven to 450F. Toss the diced kohlrabi with olive oil, garlic and salt in a bowl. (The kohlrabi can be tossed with oil and seasonings right on the pan but uses more oil.) Spread evenly on a rimmed baking sheet and put into oven (it needn't be fully preheated) and roast for 30 - 35 minutes, stirring every five minutes after about 20 minutes. Sprinkle with a good vinegar.