Duck Breasts in Creamy Mustard-Lingonberry Sauce

Sorry if this is quite similar to a recent recipe. I liked the creamy mustardseed combination over butter spätzle, so I thought I'd give it another whirl with the duckbreasts - a meat I love but that I've grown rather tired off in its common manifestations.
The trick here is to keep the meat really moist and tender. It's going to cook, but only just since it will be stripped of its fat (sacriledge!) and will dry easily.

• 2 white onions, very finely diced
• 6 white mushrooms, very finely diced
• 1 duck breasts, trimmed off all fat and cut in very thin slices (most of it comes off without any implements, but for about 1 cm has to be removed with a sharp knife)
• 1 cup of cream
• 1 leaf of laurel
• 2 tablespoons of ground mustardseeds
• 2 tablespoons of lingonberry jam or preserve, available at IKEA ;).
• salt, pepper, butter, olive oil

Fry white onions in butter and olive oil until glassy, then add mushrooms until they let water, add laurel leaf, mustardseeds, season with salt and pepper. Reduce and lower heat. Place slices of duck on top of everything in the pan, add the cream. Let simmer for about 5 minutes until the meat has just browned enough to be eaten (do not overcook).
Serve over butter spätzle