Preheat oven (electric cooker: 200 °C/circulating air: 180 °C/gas: see manufacturer). Cut four pieces of baking paper (approx. 30 x 30 cm).
Warm the jam in a pot, stir with mustard until smooth. Peel onion and cut into strips.
Wash the chicken fillets, dab dry and season with salt and pepper. Spread them in the middle of the paper pieces. Spread the jam mixture on the fillets, add the onion.
Wrap baking paper over the fillets and seal the packages well (e.g. with kitchen string). Bake in a hot oven for about 25 minutes.
Sort the arugula, wash and spin dry. Arrange around the fillets with olives. Serve with roast potatoes.