Pour the sour cream and the crème fraiche in a big bowl and stir together.
Add the salt, the black pepper and the flour while stirring.
Place the topping in the fridge for minimum two hours.
Crumb the yeast in a bowl, add some of the water and stir until the yeast is resolved. Let the yeast rest for thirty minutes.
Pour the flour, salt, the yeast, water and rapeseed oil in a big bowl and work it all together to a smooth dough.
Cover the bowl with a wet towel. Let the dough rest in the oven without heat for one hour.
Take out the dough from the oven, divide the dough in seven balls.
Start the oven at 250 degrees Celsius.
Roll the dough very thin on a baking paper like a pizza dough.
Cut the onions in thin slices.
Cut the smoked pork or bacon in thin small pieces.
Spread the topping liquid evenly on the bottoms.
Sprinkle the pork and onion evenly on the flammekueche.
Sprinkle rapeseed oil on the top.
Put the first flammekueche in the middle of the oven for fifteen minutes.
Take the flammekueche from the oven and cut it in six to eight slices and serve it immediately.