Heat oven to 230C/210C fan/gas 8. Toss the potatoes and pepper with 1 tbsp oil and 1 tsp herbs on a large baking tray. Roast for 25 mins, turning once, until the chips are golden and the pepper soft.
Meanwhile, mix the mince, two-thirds of the garlic, the paprika, egg, remaining herbs and seasoning in a bowl. Shape into 4 burgers. Can now be frozen. Heat a frying pan, add 1 tsp oil, then cook for 15 mins, turning halfway. Mix the mayonnaise with the remaining garlic.
Season the chips. Serve the burgers in buns with lettuce, onion, red pepper and garlic mayo with the chips alongside.