20g / .71ozgelatin sheets, bloomed in ice cold water
Line a half sheet pan with a nonstick rubber mat. Place a 25cm / 10in by 38cm / 15in by 6-mm / .25-in frame inside the sheet pan. The frame should be big enough to fit just inside the sheet pan.
Bring the passion fruit purée and lemon juice to a boil. Whisk together the eggs and sugar. Pour the purée and juice over the eggs and sugar while whisking constantly.
Cook the mixture over a hot water bath until thickened, stirring with a whisk occasionally. Add the diced butter and stir until combined. Pass through a fine-mesh strainer and add the bloomed gelatin sheets, stirring until completely dissolved. Pour into the prepared frame, evening out the surface with an offset spatula so that the curd is at the same level as the top of the frame. Place an acetate sheet on top of the curd and freeze.
Once frozen, remove the acetate sheet and cut into rectangles 1.75cm / .68 in by 12.5cm / 5in using a thin slicing knife. Reserve frozen.