For the pumpkin seed vinaigrette, peel and dice the onions and blanch in a little water for 1-2 minutes. Drain. Mix lime juice, vinegar, salt and pepper. Mix in pumpkin seed oil. Stir in diced onions.
For the mustard cream, mix medium hot mustard with mayonnaise and crème fraîche.
For the crisps, peel and wash the potatoes and slice or cut them into thin slices. Briefly blanch in the pot with a little water. Drain, dab dry well. Heat the oil in a pan. Fry the potato slices until golden brown and crispy.
Lift out, drain on kitchen paper and season with salt.
Clean, wash and drain the lamb's lettuce. Mix with the vinaigrette. Arrange the fillet of beef on top. Drizzle the mustard cream over it with a spoon. Sprinkle with pumpkin seeds. Add potato chips.
Baguette goes with it.