Peel the kohlrabi and cut into sticks. Peel and finely chop the onion. Knead mince, mustard, diced onion, egg and breadcrumbs, season with salt and pepper. Form small balls of the minced meat mixture with wet hands.
Cook the pasta in boiling salted water according to the instructions on the packet. Cook the kohlrabi for about 4 minutes. Heat oil in a pan and fry the meatballs in it for 7-10 minutes. Drain the noodles and kohlrabi and mix with the pesto.
Finally, add meatballs. Season everything with salt and pepper.