For the dough, knead margarine, flour and 4 tablespoons of water to a smooth dough. Roll out the dough on a floured work surface to a circle (approx. 25 cm Ø). Grease a tart tin (22 cm Ø) and sprinkle with flour. Put the dough into the tin and chill for about 30 minutes.
Cut the tofu into cubes of approx. 2 cm and cook in boiling water for approx. 5 minutes. Pour the tofu into a sieve, drain and put in a cool place. Finely mash the soy drink and the cooled tofu. Wash tarragon and chives and shake dry. Cut the chives into small rolls. Pluck tarragon leaves from the stalks and chop finely. Season the tofu mixture with salt, pepper, tarragon and chives, except for a little for sprinkling.
Clean the mushrooms and cut them in half. Peel shallots and cut them into slices. Heat the oil in a pan and fry the mushrooms and shallots one after the other for about 3 minutes each. Season with salt and pepper. Wash and halve the tomatoes
Spread the tofu mixture and vegetables into the tart. Cook in the preheated oven (electric cooker: 175 °C/ circulating air: 150 °C/ gas: see manufacturer) for approx. 40 minutes. Let the finished tart rest briefly in the mould. Cut into pieces, arrange and sprinkle with remaining chives.
Waiting time approx. 40 minutes