Ingredients

• 500g/1lb 2oz minced beef steak
• 2 large chipping potatoes
• peeled and cut into thin fries
• vegetable oil
• for deep-frying
• 4 brioche rolls
• 8 gherkins
• sliced
• 4 beef tomatoes
• sliced
• ½ round lettuce
• leaves separated
• 1 red onion
• sliced
• 1 tbsp olive oil
• ½ shallot
• chopped
• 1½ tomatoes
• chopped
• 1 garlic clove
• crushed
• 1 tbsp balsamic vinegar
• 1 tsp brown sugar
• 3 egg yolks
• 2 tsp Dijon mustard
• 150ml/5fl oz light olive oil
• 100ml/3½fl oz sunflower oil
• 50ml/2fl oz truffle oil
• 2 tbsp lemon juice
• few shavings of black truffle (optional)
• salt and freshly ground black pepper

Directions

• For the burger and fries
• put the mince in a large bowl and season with salt and pepper. Use your hands to shape the mince into four burger-shaped patties. Wrap the patties individually in cling film and place in the fridge for an hour.
• Meanwhile
• for the tomato chutney
• heat the oil in a small pan. Add the shallot
• tomatoes and garlic and cook for 5-8 minutes until softened. Add the vinegar and sugar and cook for 3-5 minutes until the chutney has caramelised slightly.
• For the truffle mayonnaise
• put the egg yolks
• mustard and a pinch of salt and pepper in a food processor and combine. Mix the oils in a jug
• then
• with the motor running
• slowly pour oil through the feed tube until you have a thick emulsion. Mix in the lemon juice and a little warm water to loosen
• if necessary.
• The mayonnaise will keep for up to 2 days in the fridge. Just before serving
• stir in the truffle shavings.
• When you are ready to cook the burger and fries
• heat the vegetable oil in a deep-fat fryer to 190C. Alternatively
• heat the oil in a deep saucepan until a cube of bread sizzles and turns brown when dropped in. (CAUTION: Hot oil can be dangerous; do not leave unattended.)
• Carefully add the potatoes to the fryer and cook for 2-3 minutes
• or until just coloured and crisp. Remove from the pan using a slotted spoon and set aside to drain on a plate lined with kitchen paper. Season with salt.
• Heat a large frying pan with a little oil. Cook the burgers on each side for 2-3 minutes
• or until cooked to your liking (you can serve the burger rare as you are using fresh steak mince).
• To serve
• put each burger in a brioche roll topped with the gherkins
• tomato slices
• chutney
• lettuce
• a few onion slices and the truffle mayonnaise. Secure with a wooden skewer and serve with the fries.