Knead flour, salt, butter, sugar and egg to a smooth dough. Put in a cool place for 1 hour. Roll out dough to a circle (28 cm Ø). Grease a tart tin (24 cm Ø) with a removable base.
Put the dough in and press the rim. Place baking paper on the dough and sprinkle with dried peas. Pre-bake the dough in a preheated oven (electric: 175 °C/ gas: level 2) for 10 minutes. In the meantime, stir eggs, sugar and cream until creamy.
Stir the lime juice and zest into the egg mixture. Take the tart out of the oven, remove the baking paper and peas. Pour lime cream on the dough. Bake the tarte for another 20 minutes at the same temperature.
Let the lime tart cool down. Sprinkle with brown sugar before serving. Decorate with lime slices and lemon balm. Makes 12 pieces.