Peel the onion and cut it in half.
Trim the celery stalk and cut it into 4 sections.
Peel the potatoes, rinse them, put them in a saucepan with the onion and celery, the dill stalk without the leaves, the Espelette pepper and the saffron threads wrapped in cheesecloth.
Cover with cold water, bring to a boil and cook for 20 to 30 minutes.
At the end of this time, remove the aromatic garnish and the saffron, mash the fingerling potatoes with a potato masher or, failing that, with a fine-grid vegetable mill.
Add the butter in pieces, then the cream, mix gently.
Reheat over low heat in a bain-marie.
Garnish with sprigs of dill and sprinkle with fleur de sel, serve immediately.
