Trim the ends from the green beans, thin them if needed, wash, and break into halves or thirds. Steam for 8-10 minutes or boil in salted water for 15 minutes, until al dente.
Drain the herring fillets, halve lengthwise, and cut into angled pieces.
Peel and slice the onion into rings, separating them. Cut tomatoes into small wedges.
Drain the cooked green beans and dress while hot with oil and vinegar. Arrange on plates, topping with herring pieces and tomato wedges.
Skip added salt due to the pickled herring, but season generously with pink and white peppercorns. Sprinkle with chopped parsley and finely snipped chives.
Serve warm or chilled for a vibrant spring dish.
