Method
Prep. Preheat the oven to 200°C (180°C fan). Line your Swiss roll tin with baking paper, snipping the corners so it sits neatly, and grease lightly.
Whisk. Whisk the eggs briefly to combine, then add the sugar. Keep whisking until the mixture is pale, thick, and leaves a trail when you lift the whisk. About 8 to 10 minutes with an electric whisk. Don't rush this.
Fold. Sift the flour and salt together, then fold gently into the egg mixture with a large metal spoon, using light, high folds to keep the air in.
Bake. Pour into the tin, spread to the edges, tap gently to release big air bubbles, and bake for 7 to 8 minutes until golden and springy.
Roll. While it bakes, lay out fresh baking paper and sprinkle generously with caster sugar. The moment the sponge is out of the oven, run a knife round the edges and tip it onto the sugared paper. Peel off the lining paper.
Warm the jam for 20 seconds in the microwave so it spreads easily. Spread over the sponge, leaving a small border. Score a line about 1cm from one short edge (don't cut through, just mark it), then roll tightly from that edge using the paper to help.