To make the pastry, combine the flour and butter in a food processor and pulse until the mixture resembles coarse breadcrumbs. Add a few tablespoons of cold water and pulse until a mass forms. Remove the pastry to a bench and knead very lightly until the mass forms a smooth dough. Cover with plastic wrap and refrigerate for at least 30 minutes.

Heat the butter in a large frying pan over low heat and add the onions. Fry slowly, stirring occasionally, for 30-45 minutes, until the onions caramelise to a dark golden brown. Add the red wine and increase the heat to medium. Cook the onions in the red wine, stirring and scraping any dark, crusty bits from the bottom of the pan. Continue to cook until the wine is evaporated and the onions are jammy. Remove the onions from the pan and allow to cool.

Heat your oven to 200˚C. Roll the pastry to less than 1cm thickness and press into a 25cm fluted tart tin. Trim any excess pastry, prick the base with a fork and lay a sheet of baking paper on top. Add pastry weights, dried beans or uncooked rice to the top of the baking paper and bake for 15 minutes. Remove the weights and baking paper and bake for a further 10 minutes until golden brown.

While the pastry is cooking, beat the eggs until well combined. Add the cream and whisk to combine, then fold in the cooled onions, the thyme leaves (stripped from the sprigs) and the cheese. Pour the filling into the pastry case and bake for around 20 minutes, until set in the centre. Remove from the oven and allow to cool slightly. Serve slices of the quiche with dressed salad greens.