Combine the dried mint, cumin, salt, lemon juice, and crème fraiche to make the dressing. Chill until ready to serve, the longer the better.
In a large saucepan of boiling, salted water, cook the potatoes for 10 to 15 minutes, or until soft. Drain, then return to the heated, dry pan for 15 minutes to dry and chill.
Cut the potatoes whichever you like (or leave them whole if they're little). Toss gently with the dressing after it has cooled to room temperature.
Sprinkle the fresh herbs on top, finish with a pinch of salt, and enjoy.