Stir the sour cream together with the crème fraiche in a big bowl.
Pour the salt, the black pepper and the flour in the bowl while stirring.
Put the topping in the fridge for minimum one hours.
Crumb the yeast in a big bowl, add some water and stir it together. Let it rest for thirty minutes.
Mix flour, salt and pepper in a bowl.
Add the water and the yeast in the bowl with flour and work it to a smooth dough.
Place a towel on top of the bowl and let the dough rest in the oven. Don´t start the oven.
When you take out the dough from the oven, divide it in eight equal pieces.
Roll each piece of the dough in very thin round bottoms. Put the bottoms on baking papers on a baking sheet.
Cut the smoked pork and the onions in thin slices.
Spread the topping liquid evenly on the eight bottoms.
Place evenly the onions, smoked pork and the mushrooms on topping liquid.
Sprinkel the cheese on the tarte flambées.
Sprinkle the rapeseed oil in very thin lines as a last touch.
Put the first tarte flambée in the middle of the oven for approx. twenty minutes. The edges should become slightly brown in color.
Take out the tarte flambée from the oven and serve it straight away.
Place the second tarte flambée in the oven while eating the first one, and continue like this with the rest while eating.