For the pastry: Measure out 100 grams of butter, then wrap it in foil of baking paper and put it into the freezer for 30 minutes. Once it’s firmed up, sieve the flour, strawberry powder and salt together, then grate in the butter on a large grater, dipping it into the flour as you go so that it doesn’t stick to the grater. Add enough iced water to just bring the pastry together into a ball, then wrap it in cling film and put it into the fridge. After 30 minutes, roll the pastry out on a floured surface to 5 millimetres thick, or just bigger than your tart dish. Use the dish as a template to cut out the pastry lid, just the right size to fit inside. Line a plate with cling film and put the pastry on top, cover the top with cling film and freeze while you prepare the strawberry filling.
For the tart: Preheat the oven to 220/200C fan. Hull the strawberries and put them to one side.
Put the sugar into the skillet and heat it up on the hob so that the sugar melts and turns a dark caramel colour, it may start to smoke - don’t worry, this is normal. Stir it a few times if you need to, to help the sugar melt evenly. Switch off the heat as soon as it’s all brown then arrange the strawberries in a circular pattern on top of the caramel. Dot the cubed butter on top, then take the pastry out of the freezer and use it to top the dish. The pastry edges will thaw as they touch the hot dish - use a knife to tuck them down inside the edge of the dish, then use a sharp knife to poke steam holes in the top. Put the tart straight into the hot oven and cook for 20 minutes.
After baking, let the tart stand for 5 minutes then carefully tip out as much of the liquid as possible, into a heatproof bowl. Leave the tart in the dish for another 5 minutes before turning it out onto a serving plate (any longer than 10 minutes and you risk it sticking to the dish). You may need to rearrange some of the strawberries after you turn it out. The tart won’t keep very well as the pastry will go soggy so best to cook it just before you want to serve it. Serve warm, with vanilla cream.