Peel the kohlrabi, cook in boiling salted water for 20-25 minutes and remove. Cut off one lid each. Hollow out the kohlrabi with a pointed knife and finely dice the flesh.
Peel and chop the onion and sauté in hot oil. Add minced meat and fry. Season with salt and pepper. Fold in tomato paste and kohlrabi pieces. Fill the minced meat mixture into the kohlrabi.
Put the lid on it. Put the filled kohlrabi in an ovenproof dish, season the tomato pieces with salt and pepper, pour on and cook in the preheated oven (electric cooker: 200 °C/ gas: level 3) for about 15 minutes.