- 800g/1lb 12oz best-quality beef steak, minced
- 3 egg yolks
- 1 tbsp Dijon mustard
- 300ml/10½fl oz rapeseed oil
- 25g/1oz beer mustard or wholegrain mustard
- ½ lemon, juice only
- 2 tbsp vegetable oil
- 4 brioche rolls, cut in half
- 4 tbsp ready-made mild chilli relish
- ½ round lettuce, leaves separated
- 2 tomatoes, sliced
- 200g/7oz cheese slices, preferably Monterey Jack
- 8 gherkins, drained, sliced
- 1 red onion, peeled, sliced
- salt and freshly ground black pepper
- Season the steak mince with salt and freshly ground black pepper and mix in a bowl using your hands. Divide the mince into four equally-sized balls and press each one between your palms to form a patty. Place the patties on a plate, cover, and chill in the fridge for an hour.
- Thirty minutes before you want to eat, light your barbecue. Allow the flames to flare up and die down.
- Meanwhile, in a bowl, whisk together the egg yolks and mustard until well combined. Gradually add the rapeseed oil in a thin stream, whisking continuously, until the mixture thickens to a mayonnaise and all of the oil has been incorporated. Stir in the beer mustard and lemon juice, then season, to taste, with salt and freshly ground black pepper.
- When the barbecue coals are just glowing, rub the patties with the vegetable oil and cook for 3-4 minutes on each side, or until cooked to your liking. (Alternatively, cook over a high heat on a griddle pan.)
- Place each brioche onto the barbecue, cut-side down, and cook for one minute, or until chargrill marks appear on the bread. Set aside.
- To assemble the burgers, spread a little of the chilli relish onto the base of each brioche bun. Place a lettuce leaf and a slice of tomato on top, then add a burger, a slice of cheese, and a dollop of the mustard mayonnaise. Top with a few gherkin and red onion slices, then place the top half of the brioche bun on top.
- Place the burgers onto serving plates, keeping them from toppling over by spearing them with wooden skewers, if desired.