1: Prepare 400 g rhubarb and cut the sticks in half lengthways.
2: Cut the sticks through diagonally (as shown in the photo).
3: Put the rhubarb pieces into a bowl with 75 g caster sugar and mix well. Leave for 1 hour.
4: Meanwhile, roll out 300 g breton sablé biscuit dough and cut a circle 8 inches (20 cm) in diameter (Use a dessert ring of the right size to help). Preheat the oven to 390°F (200°C).
5: Lay a sheet of cooking parchment on a baking sheet and sit the circle of Breton sablé dough on this. I advise leaving the dessert ring around the biscuit to keep it in shape during baking.
6: Bake for about 20 minutes, keeping a careful eye on it towards the end, as it is important not to overcook the sablé – it should still be slightly soft. Leave to cool on a wire rack. Leave the oven on.
7: Lay the rhubarb in an ovenproof dish and pour over the syrup that has collected in the bottom of the bowl.
8: Cook for about 20 minutes in the oven until the rhubarb is tender.
9: Drain the rhubarb pieces, keeping the syrup that drains off.
10: Sit the sablé base on a baking sheet and put the dessert ring back over it.
11: Prepare 300 g fruit crémeux using apple juice instead of the fruit purée. Pour the apple crémeux onto the sablé base in the ring.
12: Arrange the rhubarb pieces on top and refrigerate for 30 minutes for the crémeux filling to set.
13: Slip a knife blade around the inside of the ring and lift off. Transfer the tart to a serving plate and glaze the top with a little of the rhubarb syrup from stage 9. Your apple and rhubarb tart is ready.
Remarks
If you prefer a thicker filling, make it with stewed apple instead of juice. This tart looks nicer if there is a mixture of green and red rhubarb. This can be achieved by "cheating" slightly: At Stage 3, use a little grenadine syrup instead of sugar for half the rhubarb.