Rinse and hull the strawberries, pat dry and halve lengthwise. Place in a blender with 1 tablespoon powdered sugar and lemon juice and puree. Beat the egg yolks with the remaining powdered sugar until fluffy. Stir in the quark and sour cream.
Beat the cream until stiff and fold it into the yolk mixture. Alternately layer the cream mixture and the strawberry puree into four tall glasses and garnish with lemon balm.