Wash the maties, dab dry and dice finely. Wash the apple. Cut the fruit flesh into thin slices all the way around to the core, then dice finely. Wash and clean spring onions.
Cut the green of the spring onion into thin strips and place in cold water. Coarsely chop the remaining spring onion and capers. Mix the capers, spring onion, apple, oil and matie and season to taste with salt, pepper and lemon juice.
Wash the lettuce leaves, shake dry and pluck into thall-sized pieces. Spread the pumpernickel taler with cream cheese and cover each with a piece of lettuce. Place the matie tartare on top and garnish with strips of spring onion.