In a large mixing bowl, add the mustard, vinegar and creme fraiche. Season with salt and pepper and mix well.
Finely slice the cabbage and scallions, and toss with the creamy mustard dressing. Mix through the poppy seeds and adjust the seasoning to your taste—you might like it more creamy, acidic, salty or peppery, trust your instinct here!
Serve as a salad, with your favourite grilled meat, or these pork patties.