Combine all pastry ingredients in a mixing bowl except the water, add water as you mix until the dough is quite firm.
Heat oil in a pan add chopped onions, peeled and chop potatoes, carrots, kohlrabi and the rest of the ingredients, add 1-2 tbsps. of water to the pan as you sauté for 15mins until tender not too soft, mixture should be dry and not wet.
Heat oven to 180 degrees. On a floured surface cut into small round ball shapes, take one ball at a time and roll out, put in filing into little balls and roll one ball at a time until flat, put in filling on one half of the flatten dough, fold over with the uncover side, use a folk to press and lock patties. Repeat process, and put in the oven to bake for 20 minutes.