Kneat flour, water, olive oil, apple vinegar and salz into a dough. Let it sit covered for an hour.
Preheat the oven to 190°C.
Cut mangold and onion into fine strips. Chop parsley.
In a bowl mix together mangold, onion and parsley as well as olive oil, salt and pepper.
Divide the dough into two equal pieces. Roll out the first half very thinly into a 30cm round shape and put on a baking sheet. Cover the dough evenly with the rest of the ingredients. Leave about 2cm of the edges uncovered.
Roll out the second part of the dough the same way as the first one. Fit it on top of the other and combine both of the edges all around.
Bake for 20 minutes until the dough starts to get brown.
Brush the top with a bit of olive oil and serve with some pine nuts.