For the sauce, wash the herbs, shake dry. Pluck leaves or flags from the stems and chop all herbs. Clean and wash spring onions and cut into fine rings. Cut cress from the bed. Finely chop gherkins and capers. Mix everything and put 1/3 aside for garnishing
Mix mayonnaise, yoghurt and gherkins liquid in a bowl. Stir in herbs, cress, spring onions, gherkins and capers. Season to taste with salt, pepper and sugar
Cover each slice of bread with 3 slices of roast beef. Add 3 tablespoons of sauce to each slice and garnish with the remaining herb mixture. Sprinkle with pepper. Potato chips taste good with it