Mix the buttermilk, egg yolk, cornstarch, sugar and lemon peel well in a saucepan and bring to the boil, stirring constantly. Bring to the boil briefly. Season to taste with lemon juice. Let cool down while stirring frequently.
Peel the kiwi and cut into slices. Wash the carambola and cut into slices. Wash the currants and pluck from the panicles.
Divide the buttermilk cold bowl on 4 deep plates and garnish with the fruit.