Leek, gruyère and asparagus flamiche

Halve, wash and chop the leeks; slice the onion

Grate the garlic and finely chop the tarragon

Gently melt the butter with a splash of oil in a deep frying pan over a medium heat

Add the leeks and onion with a generous pinch of fine salt

Cook until they are soft and taking on a tint of brown

Add the sugar and vinegar, and cook until the liquid has been absorbed

Remove the onion and leeks to a large mixing bowl and leave to cool to room temperature

Heat the oven to 220C/200C fan/gas 7

Roll the pastry onto a baking sheet, keeping the paper underneath

Use a knife to score a 1cm border around the pastry

Add the garlic, tarragon and crème fraîche to the leeks, mixing well

Mix in 150g of gruyère and the eggs

Spread the mixture onto the puff pastry, ensuring everything stays inside the scored border

Slice the asparagus heads through the middle, then lay them criss-crossed over the top of the tart

Put an olive in the middle of each diamond, sprinkle over the remaining gruyère, then sprinkle over the nutmeg

Bake, turning the baking sheet halfway so it bakes evenly, until golden brown on top and puffed up in the middle

Leave to rest for 5 mins before slicing

Enjoy either hot or cold with a dressed green salad, if you like