Mix the flour with the salt, add water and olive oil and knead for at least 10 minutes to a smooth dough. To ensure the dough can be rolled out well it is important that it got the right texture.
Because each flour is different you may need to add a little more water if the strudel dough is too dry. If it is too sticky just add a little more flour. Cover the dough with a damp cloth or wrap it in plastic and rest at room temperature for one hour. It helps to keep it nice and smooth, if you further coat the dough with a little bit of olive oil.
In the meantime you can prepare the filling by halving the savoy cabbage, cutting out the stalk and cutting the cabbage into thin strips. Peel the potatoes, then cut into cubes and dry well. Fry the potato cubes in a large coated pot with a bit of olive oil. Peel the shallots and chop finely. Once the potatoes have gotten some color and roasting flavors, add the onions and cabbage into the pot and fry until the cabbage deflate. Deglaze it with white wine, pour in the vegetable stock and stew everything for another 2-3 minutes. Fold the crème fraîche in, season with plenty of salt and pepper and allow to cool.
Sprinkle a large tea towel with flour, place the strudel dough on it and roll the dough rectangularly with a floured rolling pin. To make the dough even more gauzy you can gently stretch it using the back of your hands. You can use your forearms to support it. You have to be very careful so that the dough would not rip apart. Turn the rolled dough upright to have the short side either up or down. Cut off the thicker edges and spread the potato-cabbage filling allover the dough. Leave a 2-3cm margin at the long sides and leave the top of the dough broadly blank, so that the strudel gets a double coating. Melt the butter and brush the edges of the strudel dough. Roll the strudel using the tea towel and squeeze at the ends. Now roll the filled strudel from the tea towel to a baking sheet lined with baking paper. Spread it with the remaining butter and bake in a preheated oven at 180°C for 45-50 minutes.

FoR 4 Servings

FOR THE STRUDEL DOUGH

100 g wholemeal spelt flour

200 g spelt flour

1/2 tsp salt

150 ml lukewarm water

3 tbsp extra virgin olive oil

65 g butter

FOR THE FILLING

1 kg savoy cabbage

1 kg waxy potatoes

1/4 tsp ground caraway seeds

2 shallots

2 tbsp white wine

100 ml vegetable stock

150 g crème fraîche

salt

black pepper