MAKE THE SWEET SHORTCRUST PASTRY
In a food processor, pulse together the flour, powdered sugar, and salt until combined. Add the cold cubed butter and pulse in short bursts until the mixture resembles coarse breadcrumbs with some pea-sized pieces remaining.

In a small bowl, whisk together the egg yolk, cream, and vanilla. With the processor running, pour through the feed tube and process just until the dough begins to clump together. Do not overwork.

Turn the dough onto a lightly floured surface and gather into a flat disc. Wrap tightly in plastic wrap and refrigerate for at least 1 hour, or overnight.

Remove dough from refrigerator and let soften slightly for 5 minutes. Divide into 6 equal portions (about 65g each). Roll each portion into a circle about 3mm (⅛-inch) thick and large enough to line your tart pans with slight overhang.

Carefully press the dough into each tart pan, pushing it gently into the fluted edges. Trim excess pastry by rolling a rolling pin across the top of the pan. Prick the bottoms with a fork and refrigerate for 30 minutes.

Preheat oven to 190°C (375°F). Line each tart shell with a small square of parchment and fill with baking beans or pie weights. Blind bake for 15 minutes.

Remove the parchment and weights. Return to the oven and bake for an additional 8-10 minutes, until the pastry is golden and fully cooked. The bases should be dry to the touch with no gray, uncooked patches. Allow to cool completely in the pans.

MAKE THE RHUBARB & STRAWBERRY CURD
In a medium saucepan, combine the chopped rhubarb, strawberries, and half the sugar (75g). Cook over medium heat, stirring frequently, until the fruit breaks down completely and becomes jammy, about 12-15 minutes. The rhubarb should collapse into soft strands.

Press the fruit mixture through a fine-mesh sieve into a clean bowl, extracting as much liquid and pulp as possible. Discard the fibrous remains. You should have approximately 180ml (¾ cup) of vibrant pink-red purée.

In a clean medium saucepan off heat, whisk together the egg yolks and remaining sugar until pale and slightly thickened, about 2 minutes.

Gradually whisk in the fruit purée and lemon juice until smooth. Place the saucepan over medium-low heat and cook, stirring constantly with a wooden spoon or heatproof spatula, until the curd thickens enough to coat the back of the spoon and reaches 77-80°C (170-175°F). This takes 8-12 minutes. Do not let it boil or the eggs will curdle.

Remove from heat and immediately stir in the butter, one piece at a time, until fully incorporated. Stir in the pinch of salt.

Strain the curd through a fine-mesh sieve into a clean bowl to ensure silky smoothness. Press plastic wrap directly onto the surface to prevent a skin from forming. Refrigerate until completely cold and set, at least 2 hours or overnight.

ASSEMBLE THE TART BASES
Once the curd is cold and the tart shells are completely cool, divide the curd evenly among the shells, filling to about two-thirds full to leave room for the meringue. Use an offset spatula to smooth the tops. Refrigerate while you prepare the meringue.

MAKE THE STEM GINGER SWISS MERINGUE
Fill a medium saucepan with about 5cm (2 inches) of water and bring to a gentle simmer. Combine the egg whites, sugar, and cream of tartar in the bowl of a stand mixer or a large heatproof bowl. Set the bowl over the simmering water, ensuring the bottom does not touch the water.

Whisk constantly by hand until the sugar is completely dissolved and the mixture reaches 71-74°C (160-165°F). To test, rub a small amount between your fingers and it should feel completely smooth with no graininess.

Transfer the bowl to your stand mixer fitted with the whisk attachment. Beat on medium-high speed until you achieve stiff, glossy peaks and the bowl feels cool to the touch, about 7-10 minutes. The meringue should hold its shape firmly when the whisk is lifted.

Reduce speed to low and drizzle in the stem ginger syrup and vanilla extract. Mix just until incorporated, about 30 seconds. Be careful not to overbeat or the meringue may become grainy.

FINISH AND TORCH THE PIES
Transfer the meringue to a piping bag fitted with a large star tip. Pipe generous swirls onto each tart, starting from the edges and working toward the center, building height as you go. Alternatively, use a large spoon to dollop and swirl the meringue decoratively.

Using a kitchen blowtorch, carefully caramelize the meringue peaks. Hold the torch about 8-10cm (3-4 inches) from the surface and keep it moving constantly to achieve an even golden-brown color without burning. Work in small sections, rotating each tart as needed.

If desired, garnish with a few small pieces of diced stem ginger or thin strawberry slices. Serve immediately, or refrigerate for up to 4 hours before serving.