Hazelnut Meringue Roulade and Mango Sauce

75g / 3 oz shelled hazelnuts
1 tsp cornflour
1 tsp vanilla extract
1 tsp white wine vinegar
whites of 4 large eggs
150g / 5 oz caster sugar icing sugar, for dusting

For the filling:
1 large or 2 medium ripe mangoes
2 tbsp caster sugar
1 tsp finely grated orange zest
200ml tub of creme fraiche

For the sauce:
1 large ripe mango
2 tbsp caster sugar
4-6 tbsp orange juice

Preheat the oven to 160ºC / fan oven 140ºC / gas mark 3. Line a 23 x32.5cm / 9 x13 in shallow oblong cake tin with baking paper, snipping corners to fit.

Toast the hazelnuts in a small dry frying pan until light golden flecked with brown. Tip into a food processor and grind to a fine powder.

Blend the cornflour, vanilla and vinegar to a smooth paste. Whisk the egg whites in a clean dry bowl until standing in stiff peaks. Whisk in the sugar, a little at a time, adding a little of the cornflour mixture each time until all the sugar and paste is added. The meringue will be nice and thick, very white and stiff. Reserve 2 tablespoons of the ground hazelnuts, then lightly fold the rest into the meringue with a metal spoon or the whisk blades until just mixed.

Spoon the meringue into the prepared tin and level the surface with the back of a spoon. Don't worry about making it too smooth as the craggy texture makes a lovely crust when baked. Sprinkle with the reserved nuts.

Bake for about 25 minutes, until the meringue is pale golden on top and feels crisp and dryish when lightly touched. Lay a sheet of baking paper on a work surface, remove the meringue from the oven and turn it out on the paper. Peel off the lining paper and leave to cool uncovered. (It will sink slightly.)

Make the filling: halve the mango either side of the stone, then peel and stone. Chop the flesh into small cubes and mix with the sugar and orange zest. Lightly fold in the creme fraiche. Spread over the meringue to within 1 cm / 1/2 in of the edges. Roll up from the narrow edge, using the paper to help you (the meringue will crack slightly). Put on a serving plate and dust with icing sugar.

Make the sauce: peel and stone the mango. Chop the flesh and whiz in a food processor with the sugar and orange juice. Sieve and serve with roulade slices.