Preheat oven to 375.
In a large baking dish put cut kohlrabi and potatoes (if the potato halves are too big, simply cut them in half again.)
Sliver the garlic cloves (or you could press them) and distribute them over the potatoes and kohlrabi, then zest the lemon.
Now take the olive oil and pour it over the potatoes and kohlrabi (I like to do about three turns of the wrist - each turn is about a tablespoon.)
Sprinkle fresh herbs and salt and pepper over the content of the baking dish and then stir it around once or twice so that herbs and seasoning are evenly distributed throughout.
Bake for 25 minutes, remove from oven and stir the potatoes and kohlrabi, then bake again for another 20 minutes. Check for doneness - a fork should go into the potatoes easily. Remove from oven and allow to cool for a few minutes before serving.