Rich, piquant rémoulade salads, usually made from celery root, are in season when the ground ices over and the only vegetables available are fibrous roots. If you ever wonder whether all vegetables really can become salads, stop and look at a celery root, with its grizzled, warty skin. In France, it's waited for all year long, itself a reason to look forward to the arrival of shorter days.
Peel the vegetables. If it is celery root, cut the skin off with a knife. Cut them into thin slices, then into matchstick-sized pieces. Put the pieces in a bowl, douse them well with white wine vinegar, and season with a little salt.
Let them sit for half an hour, mixing occasionally, then put the vegetables into a colander to drain. Press down on them well, several times, then transfer to a mixing bowl. Mix in the crème fraîche or mayonnaise, adding more to taste as needed, a lot of black pepper, and the chopped capers. Just before serving, add a squeeze of lemon juice and a drizzle of olive oil.