For the apple buttermilk summer drink, first prepare the applesauce. To do this, roll the lemon with the palm of your hand over the kitchen counter (gives more juice), cut in half and squeeze.
Prepare the apples (wash, peel, quarter and core) and cut into small pieces. Simmer in a saucepan with a little water and lemon juice for about 9 minutes until the apple pieces break down.
Stir and add water if necessary so that nothing sticks. Stir the applesauce (pass it through a liquid softener, pass it through a sieve or puree it) and sweeten it if necessary.
Mix the cooled applesauce with the buttermilk and add mineral water. Portion the drink and garnish.