In a saucepan, bring 1/4 l of water and 1/4 l of milk to a boil. Pour in the polenta.
Simmer briefly while stirring, stir in the ginger and sugar, then remove from heat and let cool. Remove the ginger.
In the meantime, peel the pineapple, remove the stalk and chop the pineapple flesh. Mix with yogurt, sugar and lemon juice.
Sprinkle the cooled polenta with cocoa. Add one egg and mix well.
Cut into dumplings and cook in sugar water. Remove the dumplings with a sieve ladle and arrange.
Serve the polenta dumplings on pineapple salad.