1. In a food processor, pulse the flour, diced butter, sour cream and salt until it looks like coarse sand. Add cold water 1 tablespoon at a time, pulsing, until the dough comes together in a ball. Flatten into a round disc, wrap and chill for 30 minutes.

2. Heat the olive oil in a large frypan and cook the leek and zucchini for 5 minutes until softened. Add the silverbeet, sea salt, pepper and a dash of water, and cook over low heat, covered, for 5 minutes, tossing occasionally until the leaves soften and wilt. Drain off any juices and set aside to cool.

3. Heat the oven to 200C fan-forced (220C conventional). Place the pastry on a large sheet of floured baking paper and roll out to about 28cm wide. Brush with mustard and scatter with parmesan.

4. Spoon the leek, zucchini and silverbeet filling onto the pastry, leaving a 4cm border around the edges, then crimp and fold the edges of the pastry towards the centre to form a rim.

5. Beat the egg and cumin with a dash of water and use the mixture to brush the rim. Scatter with fennel seeds and sea salt. Pour the remaining egg over the vegetables, and scatter diced cheddar over the top.

6. Use the baking paper to gently lift the galette onto a baking tray. Bake for 10 minutes then reduce to 170C fan-forced (190C conventional) for a further 20 minutes, or until nicely browned. Allow to cool for 10 minutes before slicing.

Tips

Leeks bring a lovely vegetal sweetness, but you can also use onions. Just cook them twice as long as the leeks to bring out their natural sugars.

Save the silverbeet stalks for another meal, tossed in a pasta sauce, perhaps.

The bitier the cheese, the better. This is a good way to use up scraps of cheddar, gruyere or blue cheese in the fridge.

If the vegetable filling is too juicy, it will sog up the crust, so drain off any excess juice. It's the combination of crisp crust and soft, cheesy greens that's the magic.

You want to get fancy? Scatter with toasted walnuts and serve with home-made tomato sauce.