1. Set oven to 220 degrees.
2. Roll out the puff pastry on a lightly floured surface to a thickness of about 2mm. Cut into a 25cm circle (you can use a plate or cake tin as a guide). Place on a lightly greased baking sheet and refrigerate.
3. Heat a drizzle of olive oil in a pan and fry the red onion on a medium heat for 3 mins or until softening and starting to take some colour. Season and add half a teaspoon of sugar.
4. Bring a large pan of water to the boil and cook the courgette slices for 30 seconds. Drain and leave to dry on kitchen paper. It's important the courgettes are dry & cool before you put them on the pastry.
5. Remove the pastry from the oven and prick the base with a fork, before spreading with the onions; there will not be enough to completely cover the base. Then arrange the courgette slices in concentric circles, starting from the outside ring, with slices overlapping each other slightly.
6. Brush with a little olive oil and season. Use the egg yolk to brush the pastry border (for that rich golden colour). You can refrigerate the tart until ready to eat at this stage, otherwise cook for 15-20 minutes in the oven.
7. Once cooked, place the whole burrata in the centre of the tart, then zest the lemon and sprinkle on top along with the chilli flakes and lemon juice.
8. Drizzle with a little more olive oil, season with sea salt and devour.
Courgette & Burrata Tart
4 as a main course or 6 as a starter
175g puff pastry
1 red onion, thinly sliced
½ tsp sugar
4-5 large courgettes, with ends trimmed, cut into 3-4mm slices
1 egg yolk
1 whole burrata
1 tsp chilli flakes
Note: You could add some fresh herbs at the end too – basil, mint or thyme would all go well.