Best of British burgers with triple-cooked chips

Name: Best of British burgers with triple-cooked chips
Prep time: 25 min
Cook time: 40 min
Total time: 1 h 5 min
Cuisine: British
Ingredients: 4 large potatoes (we used Maris Piper), cut into chunky chips; 2l vegetable oil , for frying; sea salt , to serve; 500g beef mince , best quality you can afford; 4 shallots , finely chopped; 2 tsp English mustard; 1 large egg yolk; 25g breadcrumb; 1 tbsp vegetable oil; 4 rashers smoked streaky bacon; 4 large sesame-seed buns , halved; 4 tbsp tomato ketchup; 8 slices red leicester; 1 large handful lamb's lettuce; 2 gherkins , sliced lengthways; 2 vine tomatoes , sliced lengthways; coleslaw , to serve (optional)