For the savarin with fruit, crumble the yeast and stir with a dash of milk and a teaspoon of sugar until smooth. Stir in 2 teaspoons of flour and let the dampfl rest in a warm place for about 30 minutes, covered with a tea towel.
Preheat the oven to 180°C.
Melt the margarine in a small saucepan, add the butter, milk and all the remaining ingredients for the yeast dough and knead into a smooth dough. Cover the dough with a kitchen towel and let it rise in a warm place for about 30 minutes.
Meanwhile, grease a large savarin dish and sprinkle with a little flour.
Pour the yeast dough into the savarin dish and bake in the preheated oven for about 20-25 minutes.
Wash and cut the fruit and mix with a dash of rum, lemon juice and 1-2 teaspoons of sugar.
Arrange the fruit in the cavity of the baked savarin and serve the savarin with fruit.