Peel the shallots. Heat 2 tablespoons of oil in a frying pan. Fry the shallots for about 20 minutes while turning. After approx. 5 minutes, sprinkle with sugar, allow to caramelize briefly, deglaze with vinegar and stock. Wash thyme, shake dry, remove leaves from the stalks and chop lightly. Season shallots with salt, pepper and thyme, except for a little bit for sprinkling.
Mix quark, egg, milk, 4 tbsp. oil and 1 tsp. salt. Mix flour and baking powder and knead into the quark mixture. Roll out the dough on a work surface dusted with flour (approx. 30 cm Ø). Place the dough sheet in the greased, flour-spread tart tin (28 cm Ø), press the edge slightly
Add the shallots to the tart and spread evenly. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 30 minutes. Tart