1. Grate the celeriac. Add it to a mixing bowl together with the mayonnaise and the lemon juice. Season with a pinch of pepper, garlic powder and salt.
2. Stir the remoulade well. Check the seasoning and add extra pepper or salt to taste if necessary.
3. Divide the slices of roast beef over cold plates. Garnish with the celeriac remoulade and the peeled grey North Sea shrimp. Finish with some fresh watercress and a last dash of freshly ground black pepper. Serve cold.