Preheat the oven to 100°C. Line a baking tray with baking paper.
Beat the egg whites until they are just stiff with shiny peaks.
Gradually add the caster sugar, a few tablespoons at a time, beating until stiff and glossy, then add the Soft light brown sugar, gradually one tablespoon at a time.
Scrape down the sides of the bowl and whisk in the cornflour and vinegar.
Spoon the beaten egg whites onto the baking tray, the spoonfuls should be just touching so her is a little space for expansion.
Bake for 1½ hours then turn, the oven down to 50Oc and leave for a further 2 hours. After 2 hours switch off and leave the meringue inside until completely cool.
Preheat oven to 200oC
Peel and slice fruit and arrange in a baking tray, with the spices, scatter over the zest and sugar and pour over the juice
Roast for 15 minutes or until the fruit is softened and lightly browned.
Remove and allow to cool slightly before using.
Place the sugar and water in a heavy bottom pan and heat gently until the sugar is completely dissolved.
Add the butter and stir continuelly until it stops foaming, add the cream and stir in.
Remove from the heat and add the sea salt to taste.
Place the Pavlova Slab on a platter and dust with Demerera icing sugar.
Top with the roasted fruit and drizzle with salted caramel sauce
Garnish with mint leaves and serve