Preheat the oven to 210 ° C. Knead a homogeneous dough from the dough ingredients. Shape the dough into a ball and set aside for a moment.
Cut the smoked tofu into fine cubes. Heat the olive oil in a pan and fry the tofu cubes on all sides for about 3 minutes. Set the pan aside. Mix the cashew butter with lemon juice and water until creamy and season with salt, pepper and nutmeg. Peel the onions and cut into fine rings.
Roll out the dough thinly on a lightly floured work surface to the size of a baking sheet and place on a baking sheet lined with baking paper. Brush with the cashew cream, cover with onion rings and distribute the smoked tofu evenly on top.
Bake the tarte flambée in the oven on the middle rack for about 15-20 minutes. Finally, wash the chives, shake dry, cut into small pieces and sprinkle the finished tarte flambée with them.