Boil potatoes with skin in salted water.
Peel when still hot.
Slice the potatoes.
Chop a shallot and bring to a boil in about 200 ml broth.
Add salt, black pepper, tarragon mustard, apple cider vinegar, and pumpkin-seed or olive oil.
Add warm mixture to warm potatoes.
Mix by hand so the marinade blends with some potatoes.
Let steep for a few hours at room temp so the potatoes can absorb some marinade.
Top with chives.
