Preheat the oven to 200 degrees Celsius
Start by making your burger patties. Put the mince in a bowl and add 1tsp of salt and 1tsp black pepper. Use your hands to work the seasoning into the meat, then press into four tight balls. Flatten each ball into a burger shape.
To cook the patties, put the oil in a griddle pan over a medium-high heat. Add the patties and cook for 12-14 minutes, turning regularly, until the outsides are caramelised and the insides are cooked through and juicy.
Slice the brioche buns in half.
When the patties are done, remove from the pan and put on a baking sheet. Top each burger with a slice of cheese and put in the oven for 2-3 minutes until the cheese is melted.
Put the buns in the oven for 1-2 minutes until lightly toasted.
To compile the burgers, put 2 tsps burger sauce on the bottom bun of each burger. Top with the patty and add a pile of gherkin slices. Put 2 tsps American mustard on the inside of each top brioche bun half, and place that on top. Enjoy!