Peel and finely chop the onion. Wash the thyme, dab dry and pluck the leaves from the stems. Clean, wash and cut the peppers into pieces. Knead minced meat, egg yolk, breadcrumbs, half of the onion cubes and mustard with the dough hooks of the hand mixer.
Then season with salt, pepper and half of the thyme. Form 5 meatballs from the minced meat mixture. Heat 1 tablespoon of oil in a pan. Fry the meatballs for 6-8 minutes at medium heat while turning.
In the meantime heat the remaining oil in a small pot. Fry the paprika and remaining onion for about 5 minutes over medium heat, turning them over. Remove meatballs from the pan and keep warm.
Deglaze frying fat with stock, stir in frying stock, bring to the boil, stir in sauce thickener and bring to the boil again. Season with salt and pepper. Arrange meatballs, paprika vegetables and sauce on a small plate.
Serve sprinkled with remaining thyme. Boiled potatoes taste good with it.