Wash the potatoes thoroughly, dab dry and wrap them individually in oiled aluminium foil. Bake in the preheated oven (electric cooker: 225 ° C/ gas: level 4) on the grid for 1 1/4-1 1/2 hours.
Hard boil eggs. Cut ham into fine strips. Wash the mint, put some aside for garnishing, cut the rest finely. Mix yoghurt, mayonnaise, ham and mint. Season with salt, pepper and lemon peel.
Peel, dice and fold in the eggs. Leave to stand for about 30 minutes. Clean, wash and slice the radish and cucumber. Clean, wash and chop the salad. Drain the corn. Mix everything.
Mix vinegar, salt, pepper and remaining oil. Pour over the salad. Cut the potatoes, press them apart and fill with egg salad. Garnish with mint. Add salad.