Line 3 small baking trays with baking paper and preheat the oven to 165°C. For the roulades, beat the eggs with the sugar, vanilla, pinch of salt and rum for about 6 minutes - the mixture should be thick and creamy. Sieve and mix the cornflour with the flour and baking powder and gradually fold into the egg mixture. Pour the roulade mixture onto the tray, smooth it out and bake for about 8 minutes.
Transfer the roulades to fresh tea towels and sprinkle with a little sugar. Leave the roulades to cool and spread a generous layer of strawberry jam over the top. Then cut the rolls into slices about 2 cm wide.