Method

• 1.
  For the crust, place vinegar, sugar and a pinch of salt flakes in a jug with 100ml water, stirring to dissolve sugar. Chill. Place flour and butter in a bowl and rub in until it resembles crumbs, leaving a few large pieces of butter. Turn out onto a clean work surface, make a well in centre and gradually add vinegar mixture, folding to incorporate (be careful not to melt butter). Enclose in plastic wrap and chill for 1 hour.
• 2.
  For the candied pecans, place pecans, sugar and butter in a non-stick saucepan and cook, stirring, for 6-7 minutes or until caramelised. Pour over a greased baking tray and set aside for 30 minutes to set.
• 3.
  Preheat oven to 180°C.
• 4.
  Line a baking tray with baking paper. Roughly chop 600g sweet potato, then place on prepared tray and season with salt flakes. Roast for 40 minutes or until soft, then cool completely.
• 5.
  Meanwhile, place butter in a saucepan over medium heat and cook, swirling, for 3-4 minutes or until golden and nutty. Add sugar and cook, stirring occasionally, for a further 4-5 minutes until a light caramel. Remove from heat and carefully stir in cream. Add caramel and sweet potato to food processor, and whiz until smooth and combined. Add the spices, then gradually add eggs, egg yolks and milk, and whiz until very smooth.
• 6.
  Preheat oven to 200°C.
• 7.
  Roll out pastry on a lightly floured work surface to 2-3mm thick and use to line the base and side of a round 22cm x 5cm fluted pie dish. Trim pastry, leaving a 2cm overhang, then, using your fingers, crimp the pastry edge. Line with baking paper and baking weights, and bake for 30 minutes. Remove paper and weights, and bake for a further 10 minutes or until golden.
• 8.
  Reduce oven to 160°C. Pour sweet potato filling into pastry base and bake for 45-50 minutes or until just set with a slight wobble in the centre. Cool to room temperature, then chill for 2-3 hours to set.
• 9.
  Using a vegetable peeler, peel the remaining 400g sweet potato into thin strips. Heat 1cm oil in a heavy-based frypan over medium heat. In batches, add sweet potato strips and fry for 1-2 minutes or until crisp. Remove with a slotted spoon and drain on paper towel. Cool completely.
• 10.
  For meringue, whisk the eggwhites in a stand mixer fitted with the whisk attachment until cloudy. Gradually add the sugar and whisk until the mixture is thick and glossy.
• 11.
  Spoon the meringue over pie, then use a kitchen blowtorch to caramelise. Scatter with candied pecans and sweet potato crisps to serve.