Debone the herring fillets and cut into neat cubes. Peel the potatoes and slice them thinly. Sort, wash, and spin dry the salad greens.
Peel the tomatoes and dice them. Wash and finely chop the chives. Combine the heavy cream with the diced tomatoes and chives. Season to taste with salt, pepper, and lemon juice.
Whisk together the thistle oil, sherry, salt, and pepper to make a light dressing. Gently toss the herring cubes with a bit of this dressing. Dress the salad greens and potato slices similarly.
Artfully plate the herring tartare alongside the dressed greens and potatoes, topped with the tomato cream.
For a refined touch, serve the chive cream and diced tomatoes separately so guests can mix them tableside.
Source: La Nouvelle Cuisine for All Seasons. Chanteclerc.