- 225g/8oz flour, plus extra for dusting
- 100g/3½oz butter
- 25g/1oz sugar
- 1 free-range egg
- dash milk, optional, to help bind the pastry
- 50g/2oz butter
- 1 tbsp vegetable oil
- 4 large Spanish onions, sliced
- 1 clove garlic, crushed
- salt and freshly ground black pepper
- 2 free-range eggs
- 2 free-range egg yolks
- 50g/2oz wholegrain mustard
- 150ml/5fl oz double cream
- salt and freshly ground black pepper
- 150g/5oz borlotti beans from a can, rinsed and drained
- 150g/5oz butterbeans from a can, rinsed and drained
- 150g/5oz broad beans from a can, rinsed and drained
- 150g/5oz cannellini beans from a can, rinsed and drained
- 1 tbsp chopped fresh mint
- 2 tsp Dijon mustard
- 1 lemon, juice only
- 1 tbsp white wine vinegar
- salt and freshly ground black pepper
- 100ml/3½fl oz extra virgin olive oil
- For the pastry, place the flour, butter, sugar and egg into a food processor and pulse until just coming together as a dough (add a little milk if necessary to bring the dough together).
- Bring the dough together into a ball, wrap in cling film and place into the fridge to chill for at least an hour.
- Unwrap and roll out the pastry onto a floured work surface to fit a 20cm/8in tart case. Press the pastry into the case and place into the fridge to chill for 45 minutes.
- Preheat the oven to 200F/400F/Gas 6.
- Place the chilled tart case into the oven to bake for 10-15 minutes, until golden-brown. Remove from the oven and leave to cool.
- Reduce the oven temperature to 180C/355F/Gas 4.
- Meanwhile, for the filling, heat the butter and oil together in a large, heavy-bottomed saucepan over a low heat.
- Add the onions and garlic and season well with salt and freshly ground black pepper. Cook the onions very gently for about 30-40 minutes until very soft and golden, but not browned.
- Whisk together the eggs, egg yolks, mustard and cream in a clean bowl.
- Add the slow-cooked onions to the egg mixture, then spoon the mixture into the cooked tart case. Transfer to the oven to bake for 20-25 minutes, or until the filling is set and golden-brown.
- For the bean salad, place all of the beans and the chopped mint into a large clean bowl and mix to combine.
- For the dressing, place the mustard, lemon juice and white wine vinegar into a clean bowl. Season, to taste, with salt and freshly ground black pepper and slowly pour in the oil, whisking constantly.
- Pour the dressing over the bean mixture and mix well.
- To serve, cut out four wedges of warm onion tart and place onto plates. Place a spoonful of bean salad alongside each.