Blend one third of strawberries with granulated sugar and transfer to a bowl.
Stir in Marsala and remaining strawberries, then chill for at least 30 minutes.
Preheat oven to 190°C and line a 23 x 33cm tin with greaseproof paper.
Whisk eggs, sugar, and vanilla until pale and mousse-like.
Fold in warm water using a metal spoon.
Sift flour and salt over mixture and fold in gently until just combined.
Pour into tin, level the surface, and bake for 10 to 15 minutes.
Turn sponge onto sugar-dusted paper, cool for 10 minutes, then remove lining paper.
Combine mascarpone, icing sugar, and vanilla in a bowl.
Trim sponge edges and spread with mascarpone cream, leaving a small margin.
Top with macerated strawberries and one third of the strawberry purée.
Roll the sponge tightly from the short side and place join-side down on a plate.
Dust with sugar and decorate with extra strawberries and remaining sauce.