Shallot Onion and Chive Tart

🥘 Ingredients

• all-purpose flour 225 g
• salt 1pinch
• cold unsalted butter 60 g
• cold vegetable shortening 60 g
• cold water 5 Tbsp
• shallots 8
• onions 3 large
• unsalted butter 25 g
• sunflower oil 1 Tbsp
• salt 1 pinch
• pepper
• salt
• eggs 4 medium
• egg yolks 2 medium
• heavy cream 200 ml
• wholegrain mustard 1 ½ Tbsp
• chives 1 Tbsp
• salt
• white pepper

1. 1

   To make the pastry, put the all-purpose flour into a bowl and mix in the salt . Add the cold unsalted butter and cold vegetable shortening and rub into the flour with your fingertips until the mixture resembles fine breadcrumbs. Alternatively, do this in a food processor or mixer and then transfer to a bowl.
2. 2

   Now work in just enough (3 to 5 Tbsp) cold water to bring the dough together. When it begins to stick together, gently knead it into a ball. Wrap in plastic wrap and chill in the fridge for around 30 minutes .
3. 3

   Meanwhile, for the filling, thinly slice the shallots and onions . Heat the unsalted butter and sunflower oil in a large frying pan over a medium-low heat. Add the shallots and onions with a pinch of salt and cook slowly for at least 20 minutes , stirring occasionally, until they are very soft and golden. Season with pepper and more salt if needed. Leave to cool.
4. 4

   Heat your oven to 200°C / gas 6 / 400°F and have ready a 23 cm loose-based fluted tart tin , 3.5 cm deep.
5. 5

   Roll out the pastry on a lightly floured surface to a 3 mm thickness and use it to line the tart tin, leaving the excess hanging over the edge. Keep a little uncooked pastry back in case you need to patch any cracks later. Prick the pastry base with a fork . Line the pastry with baking parchment or foil and then fill with baking beans, or uncooked rice or lentils .
6. 6

   Bake blind for 15 minutes , then remove the parchment and baking beans and return the pastry to the oven for about 8 minutes or until it looks dry and faintly colored. Trim away the excess pastry from the edge. Use a tiny bit of the reserved raw pastry to patch cracks or holes if necessary. Turn the oven down to 180°C / gas 4 / 350°F.
7. 7

   For the filing, whisk the eggs , egg yolks and heavy cream together, then whisk in the wholegrain mustard and chives . Season with salt and white pepper .
8. 8

   Spoon the cooled onion mixture into the pastry case and spread it evenly, then carefully pour on the egg mixture. Bake in the oven for 30 to 35 minutes , until the filling is just set and golden. Leave in the tin for 5 minutes , then unmold. Serve warm or cold..