If possible, use thin leeks for this classic French first course. The cooking liquid is turned into a mustard vinaigrette.
Trim and clean:
Heat in a large skillet over medium-high heat until hot but not smoking:
Add the leeks in batches and cook, turning, until golden brown, about 10 minutes. Return all the leeks to the skillet and add:
Cover and cook, turning occasionally, until the leeks are tender, about 8 minutes. Transfer to a serving platter. Add to the skillet:
Cook, stirring, for 3 minutes. Remove from the heat and stir in:
Pour the vinaigrette over the leeks and let cool. Serve at room temperature, garnished with: