Potatoes, tomatoes and caramel may sound like an unusual combination of flavours, but topped with a crab salad this makes a fabulous supper. For a light meal serve with a green salad, too.
Make the rough puff pastry. Place 75g of the butter in a bowl with the flour, basil and salt. Use your fingertips to rub together until everything is roughly mixed in. Stir in 4–5 tablespoons of very cold water and combine to form a stiff dough.
Gather the dough together into a ball and chill it in the freezer for a few minutes. Then, roll it out to a large rectangle measuring about 30 x 25cm and about 3mm thick. Grate the remaining butter over one half of the pastry. Fold the other half over the top and seal the edges, then roll out to a large rectangle again.
Fold this rectangle into thirds as if you were folding a letter and freeze for 4 minutes. Roll and fold twice more, returning the dough to the freezer for 4 minutes between each rolling. Wrap the finished dough in cling film and chill until needed.
Make the filling. Heat the oven to 150°C/130°C fan/300°F/Gas 2. Squeeze out and discard the seeds from the halved tomatoes, then place them cut side up in a baking tray. Season well with salt and pepper and drizzle with the basil-infused olive oil. Bake for 35 minutes, until tender and dried out a little, then remove from the oven and pat dry with kitchen paper.
While the tomatoes are baking, slice the potatoes using the thinnest setting on the mandolin. Heat 10g of the butter in a medium non-stick pan over a high heat, add one third of the potato slices and fry for about 5 minutes, until lightly browned. Repeat twice more with the remaining butter and potatoes, setting each batch aside until needed.
Heat the oven to 200°C/180°C fan/400°F/Gas 6. Make the caramel. Heat the butter and sugars in a small pan over a medium heat, without stirring, until golden. Pour into the base of the tarte tatin tin and spread evenly.
Arrange the potatoes on top of the caramel and season well with salt and pepper, then sprinkle over the thyme leaves and cayenne pepper. Place the tomatoes in an even layer on top of the potatoes.
Roll out the pastry to a circle about 2cm bigger than the tin and place on top of the tomatoes, tucking the edges inside the tin. Bake for 40 minutes, until golden brown, then remove from the oven and leave to cool a little in the tin for about 15 minutes.
Make the crab salad. Mix the crab meat with the lemon juice, lime zest, crème fraîche, tomato purée, dill and garlic. Stir in the chopped red chilli a little at a time, to taste.
Invert the tarte tatin out onto a plate. Arrange the crab in a ring around the outside of the tart and garnish with lamb’s lettuce leaves, cress and sliced radish.