Peel and finely chop the onion and garlic. Knead minced meat, egg yolk, cream cheese, half onion, garlic, mustard and tomato paste. Season to taste with salt and pepper. Wash the peppers.
Cut "lid" lengthwise and put aside. Clean the pods from the inside and fill them with the prepared chopping mass. Spread the stuffed peppers on a fat pan. Bring the stock to the boil in a saucepan and pour into the fat pan.
Braise in the preheated oven (electric cooker: 200 °C/ circulating air: 175 °C/ gas: level 3) for about 20 minutes. In the meantime, mix vinegar and 1 tbsp. water with remaining onion cubes. Season with salt, pepper and sugar.
Add oil drop by drop. Wash and clean the rocket. Mix vinaigrette and rocket. Finely dice the paprika lid. Arrange peppers and rocket on plates. Sprinkle with paprika cubes.