For the asparagus ragout with crème fraîche, peel the onions and chop them finely. Heat the butter in a wide frying pan and sauté the onion in it. Add the white wine and the vegetable stock.
Add the crème fraîche with the mustard, mix well with a whisk, bring to a boil and simmer gently for 5 minutes uncovered. Season vigorously with salt and freshly ground pepper.
Rinse the chives and cut into small rolls. Peel the asparagus, cut the ends into small pieces and cut the asparagus spears diagonally into 3 cm long pieces. Add to the sauce and let stand for a good 10 minutes. Before serving, stir in the chive rolls.
Dress the asparagus ragout with crème fraîche and serve.