Puy Lentils With Mustard Vinaigrette

Puy lentils are worth buying specifically: they hold their skins where softer lentils blow open and turn to purée.

The finished dish should be glossy and distinct, never wet at the bottom of the bowl.

Dressing hot lentils is the whole technique — they drink the vinaigrette as they cool and season themselves through.

Salt goes in at the end of the simmer, never at the start.