To make the pastry, sift the flour and salt into a large bowl, add the butter and rub into the flour, using your fingertips, until the mixture resembles breadcrumbs. Sprinkle with 1 1/2 tablespoons of cold water and mix using a round-bladed knife. With your hands, gather together into a firm but pliable dough, handling as little as possible. Wrap the pastry in plastic wrap and chill for 20 minutes.
Cook the carrots in a steamer, set over a saucepan of boiling water for 10 minutes. Add the broccoli and steam for a further 5 minutes until both are tender but not soft.
Meanwhile, whisk together the eggs, milk and salt and pepper to season, in a jug. Stir in the cheese. Put a baking tray in the oven and preheat to 190 degrees C.
Roll out the pastry thinly on a lightly floured work surface and use to line a 24cm loose-based flan tin. Prick the base with a fork, then refrigerate for 10 minutes. Spread the vegetables over the pastry, then pour over the egg custard.
Put the tin on the hot baking tray and bake for 30 minutes until the filling is lightly set and golden. Serve warm, garnished with fresh herbs.