Tomato, caramelised onion and Le Gruyère AOP tart

6
1 hour 40 minutes

Ingredients

Gruyère pastry

  • 250g of plain flour
  • 125g of butter, chilled and diced
  • 1 pinch of salt
  • 50g of Gruyère, finely grated
  • iced water, 1–2 tbsp

For the filling

  • 120g of butter
  • 1kg large onions, peeled, halved and sliced
  • 4 garlic cloves, peeled and chopped
  • 1 tbsp of chopped rosemary
  • 100g of Gruyère, finely grated
  • 500g of ripe tomatoes, sliced
  • olive oil, to drizzle
  • salt
  • pepper

Method

1
Make the pastry by placing the flour and butter in a mixing bowl with a pinch of salt. Rub together with your fingertips until the mixture resembles breadcrumbs. Add the cheese, stir to combine then add enough iced water to bring it together to form a dough. Wrap the pastry in cling film and leave to rest in the fridge for 30 minutes
2
Melt the butter in a large frying pan over a medium heat. Add the onions, garlic and rosemary, season with salt and pepper and stir. Cover and cook for 15 minutes, or until the onions have softened. Uncover and cook for 30–40 minutes until the onions have reduced and are golden brown. Stir frequently to ensure the onions don’t burn
3
Preheat the oven to 200°C/gas mark 6
4
Roll out the chilled pastry to line a 25cm tart tin. Prick the base with a fork a few times and line the pastry with baking parchment. Fill with baking beans and bake in the preheated oven for 10 minutes. Remove the baking beans and parchment and bake for a further 5 minutes
5
Remove from the oven and sprinkle the grated Gruyère cheese on the bottom of the pastry case in an even layer. Top with the caramelised onions. Arrange the tomato slices, slightly overlapping, on top of the onions. Season with salt and pepper and drizzle with olive oil
6
Place in the oven and bake for 40 minutes. Remove from the tart tin and serve warm with a green salad