Grease a tart mould with a removable base (26 cm Ø) and dust with flour. Knead the flour, 125 g sugar, 1 packet of vanilla sugar, 1 pinch of salt, butter in pieces and 1 egg first with a hand mixer and then briefly with your hands until smooth.
Roll out the short pastry on a little flour to a circle (approx. 30 cm Ø). Line the tart mould with the pastry, pressing the edges into the grooves. Prick the bottom of the pastry several times with a fork. Chill for about 45 minutes.
Separate 4 eggs, chill 4 egg whites. Mix ricotta, lime zest, lime juice, 125 g sugar and 1 packet of vanilla sugar. First add the quark and 4 egg yolks and then the pudding powder.
Spread the curd mixture on the shortcrust pastry. Bake in the preheated oven (electric cooker: 175 °C/circulating air: 150 °C/gas: level 2) for approx. 55 minutes. Shortly before the end of the baking time, whisk 4 egg whites and vinegar until stiff, pour in 200 g sugar and continue beating until the sugar is completely dissolved.
Pour the beaten egg white into a piping bag with a large star-shaped spout (12 mm). Remove the tart from the oven and place it on a cake rack. Turn up the oven: (Electric cooker: 225 °C/recirculating air: 200 °C/gas: level 4) Spray the beaten egg whites onto the cake close together.
Continue baking for approx. 8 minutes on the lowest rack (gas: see manufacturer). Leave to cool for about 2 hours. Dust with icing sugar.