Ingredients

• 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

Directions

• 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.