1 recipe shortcrust pastry or 300 grams bought pastry
3 large red onions, peeled with root end trimmed but left intact
2 tablespoons balsamic vinegar
3 tablespoons olive oil
sea salt and freshly ground pepper
150 ml sour cream
2 cloves garlic, crushed
1 tablespoon chopped thyme leaves
100 grams soft blue cheese
baby rocket or spinach
26 cm loose-based tart tin
Preheat the oven to 180˚C.
Cut the onions into quarters through the root end and place in a large baking dish with the vinegar and olive oil. Toss and season well. Roast for 30-40 minutes or until tender, turning occasionally. Try to keep the quarters whole when turning. Cool.
Pastry: Roll the pastry out on a lightly floured bench and line the tin. Bake blind for 20 minutes then remove the beans and paper and bake for a further 5-8 minutes or until the pastry is lightly golden and dry.
Reduce the oven temperature to 170˚.
Filling: Whisk all the ingredients, except the blue cheese, in a bowl and season.
Arrange the onions in the pastry case and gently pour over the filling. Break the blue cheese into pieces and place around the onions. Bake for 25-30 minutes until the filling is golden and set. Cool for 30 minutes.
To serve: Remove the tart from the tin, place on a serving platter and garnish with rocket.
To bake blind: line a prepared pastry case with baking paper and fill with pie weights or dried beans. The beans support the pastry as it cooks. Bake in a preheated 190˚C - 200˚C oven for up to 20 minutes before removing the paper and weights. The shell should now have taken form. Return to the oven for the time specified in the recipe.