Cut tomatoes crosswise, blanch, skin, quarter and remove seeds. Dice tomato flesh. Peel onions and garlic, chop finely. Wash lemon thoroughly, grate peel.
Squeeze the juice. Peel avocados, cut them from the core. Mash the avocado flesh in the lemon juice. Mix with the yoghurt. Stir in diced tomatoes, chopped onion, garlic, grated lemon peel and pickled pepper.
Season to taste with salt and ground chilli. Spread breads with the avocado cream. Add Black Forest Ham. Garnish as desired with lemon wedges and lemon balm.