Sieve the flour on the kitchen plate and make a hole in the middle. Put the sugar, salt and water in the middle and crumble the fresh yeast over it. After about a quarter of an hour, mix the ingredients together until the dough is really smooth (you should knead with yeast dough for about 12 minutes, because of the protein and starch compounds). Then cut the dough in two and form two balls. Cover and leave them to rest in the refrigerator for one night. Let the dough rise at room temperature about an hour before you eat it. Preheat the oven to 250 ° C. Peel the onion, cut in half and cut into thin strips. Also cut the bacon into thin strips. Mix the creme fraiche and sour cream together and finally add a spoonful of olive oil. Sprinkle the dough pieces well with flour and roll them out very thinly (I prefer to bake these in a pizza tray). Spread the cream evenly on the dough (make sure that a bit of the edge is left). Evenly distribute the onion and bacon and bake everything in the oven. I always put it at the bottom of the oven so that the base gets nice and crispy. I can't tell you how long it takes, as every oven bakes differently. It is best to enjoy a good Riesling with it.