Matcha Lemon Swiss Roll

STEP 1: MAKE THE LEMON CURD (IN ADVANCE)
Whisk lemon juice, zest, sugar, and yolks together in a small heavy-bottomed saucepan. Cook over medium-low heat, whisking constantly, until the mixture thickens enough to coat the back of a spoon (about 7-9 minutes); it should reach 80°C / 175°F — do not let it boil. Remove from heat and whisk in the cold butter one cube at a time until glossy. Strain through a fine sieve into a bowl, press cling film directly onto the surface, and chill until completely cold and thickly set, at least 2 hours or overnight. Fix-It note: this larger batch ensures lemon sharpness comes through against the matcha, as Paul Hollywood wanted.

STEP 2: PREPARE THE INLAY PASTE AND PIPE THE FLORAL DESIGN
Preheat oven to 220°C / 425°F (fan 200°C / 400°F). Line the Swiss roll tin with baking parchment, allowing 2 cm overhang on all sides. Cream the softened butter and icing sugar together until pale. Beat in the egg white, then fold in the flour to make a smooth piping paste. Divide into two small bowls and tint one a soft pink for petals and one green for leaves and stems. Transfer each colour to a small piping bag fitted with a fine round nozzle. Pipe simple floral motifs — small five-petal flowers with tiny green leaves — directly onto the parchment, leaving 1.5-2 cm of clear space between each motif so the sponge batter can flow around them. Freeze the tin for 10 minutes to set the design before pouring batter.

STEP 3: MAKE THE GÉNOISE-STYLE LEMON SPONGE
In one bowl, whisk the egg yolks with two-thirds of the caster sugar, the lemon zest, vanilla, and salt until pale, thick, and ribbon-stage (about 4 minutes on high speed). In a second clean bowl, whisk the egg whites to soft peaks, then gradually add the remaining sugar and whisk to firm, glossy peaks. Sift the flour and cornflour together. Fold one-third of the whites into the yolk mixture to loosen, then alternate folds of sifted flour and remaining whites in three additions. Use a large metal spoon and fold in a figure-of-eight, stopping the moment the batter is homogeneous — overmixing here knocks the air out and produces a tough roll.

STEP 4: BAKE THE SPONGE
Pour the batter gently over the chilled piped inlay design, starting from one corner and letting it spread to avoid disturbing the motifs. Tilt the tin to level — do not spread aggressively with a spatula. Tap once on the counter to release any large bubbles. Bake on the middle shelf for 10-12 minutes, until the sponge is golden, springy to the touch, and just shrinking from the sides. Do not overbake — a dry Swiss roll cracks on rolling.

STEP 5: ROLL THE SPONGE WARM (CRITICAL STEP)
While the sponge bakes, lay a clean tea towel on the counter, top with a sheet of parchment, and dust generously with icing sugar. The instant the sponge comes out of the oven, run a knife around the edge and invert onto the sugared parchment, design side down against the parchment. Peel off the baking parchment slowly. Score a shallow line 1 cm in from one short edge (do not cut through), then roll the warm sponge tightly into the parchment and tea towel, starting from the scored short edge. Leave to cool completely, rolled. Fix-It note: pre-rolling while warm gives a round, even roll later — Paul criticised the in-tent finish as "very much oval rather than round," which happens when the sponge is rolled cold for the first time or rolled under uneven pressure.

STEP 6: WHIP THE MATCHA CREAM
Sift the matcha into a small bowl and whisk in 2 tablespoons of the cream to make a smooth slurry — this prevents matcha lumps. In a larger bowl, whip the remaining cream with the icing sugar and vanilla to soft peaks. Add the mascarpone and the matcha slurry and whisk just until medium-stiff peaks — stop early, as mascarpone seizes if overwhipped. Fix-It note: this uses noticeably less matcha cream than the in-tent version — Paul's exact complaint was "too much of the matcha cream and not enough curd," and restraint here is what fixes the balance.

STEP 7: FILL AND RE-ROLL
Gently unroll the cooled sponge — it should hold a curl. With the inlay design facing the work surface (so the design ends up on the outside of the finished roll), spread a thin, even layer of cold lemon curd to within 2 cm of all edges. Spoon the matcha cream on top in a thin layer — resist the urge to pile it on. Scatter the sliced strawberries in a single row down the centre, parallel to the short edge you'll roll from. Roll up tightly, using the parchment to guide and apply even pressure across the whole length — even pressure is what produces a round cross-section rather than oval. Wrap the finished roll firmly in fresh parchment, twist the ends like a sweet wrapper, and chill seam-side down for at least 1 hour.

STEP 8: SERVE
Unwrap, trim each end with a serrated knife (a hot knife dipped in hot water and wiped dry gives the cleanest cut), and dust very lightly with icing sugar. Cut into 8 thick slices to serve. Best eaten the day it's made; will keep wrapped in the fridge for up to 2 days, but the sponge softens.