Preheat the oven to 140°C / fan 120°C / gas mark 1. In a clean, dry, food mixer bowl, add the egg whites and cream of tartar. Begin to whisk on low, building up to medium as the egg whites increase in volume and become stiff.
Very gradually add the 225g of sugar in four batches, whisking thoroughly after each addition. Stop when the mixture is thick, glossy and stands at a peak.
On a large parchment-lined baking tray, spread the meringue mixture into a circle measuring 20cm in diameter. Bake for 1 hour and then turn off the oven, leaving the door closed, and leave for at least 3 hours until completely cool.
In a small saucepan, add 2 tbsps of sugar and 50ml water and simmer on a low heat to dissolve (about 5 minutes). Take off the heat and allow to cool, then blitz with a third of the strawberries until smooth. Pass through a sieve to make a smooth coulis and set aside.
In a medium bowl beat the remaining 1 tbsp sugar with the double cream and rosewater until thickened, and then fold in the crème fraîche. Pile on top of the pavlova, arrange the remaining strawberries on top and then drizzle with the coulis. Garnish with a few mint leaves.