(10-12 turnovers)

First make the pastry as you will want it to chill out in the fridge for at least 30 minutes. In the bowl of a food processor pulse together the flour, salt and sugar. Cut the butter into approximately 1 cm cubes and toss in with flour. I recommend actually doing this with your fingers so they don't all lump together. Pulse the butter a few times until it is pea sized. Now stream in the water while continuing to pulse. It should form a rough dough. Remove from the processor onto a clean surface and press into a disc. Wrap tightly in plastic and refrigerate. (Note this can also be done all by hand, but trust me this is faster - plus you can use the food processor to chop the rhubarb and apple.)

Now to make the filling thinly slice the rhubarb (you can use the slicing attachment to your food processor if you like. Add to a small saucepan. Peel the apples and remove the core. Thinly slice the apples and also add to the sauce pan along with the remaining teaspoon of sugar, chopped rosemary and 3 tablespoons of water. Bring to a simmer, cover and cook on medium low for ten minutes, stirring occasionally. Remove lid and check, the rhubarb should now be softened. If the mixture is quite wet, simmer without a lid until excess liquid evaporates. Remove from the heat and cool to room temperature before using to fill the turnovers.

Preheat oven to 425F or 400F convection. Remove the pastry from the fridge and roll out to about 4mm. Cut into 4"x4" squares. Get yourself ready to form these by limning a baking sheet with parchment and assembling a station. You will need a little bowl of cold water, a fork, a paring knife and your filling with a tablespoon measure. For each turnover drop a tablespoon of filling in the middle of the square, now run a wet finger along two adjacent sides of the square. Fold into a triangle such that each dry side meets with one that you have wet. Gently press the edges. Use your fork to go around the edges and press. Now with your paring knife gently cut a few slits in the top of the turnover. Transfer to the baking sheet. Repeat with remaining squares. Whisk together the egg and teaspoon of cream and brush each turnover lightly with the mixture. Bake for ~25 minutes or until crispy and golden brown. Cool on a rack.