Tomato galette recipe

Ingredients

• 30 g unsalted butter
• 1 small red onion, peeled and thinly sliced
• 1 tbsp thyme leaves
• 3 tbsp plain (all-purpose) flour, for dusting
• 300 g shortcrust pastry
• 100 g cheddar cheese, coarsely grated
• 1 small bunch of tarragon, leaves picked
• 1 small, firm courgette (zucchini), thinly sliced
• 250 g small to medium tomatoes, thinly sliced (a mixture of colours and sizes is nice)
• 1 glug of olive oil
• 1 pinch sugar
• 1 egg yolk, beaten, to glaze
• 1 pinch salt and freshly ground black pepper