Beef Burgers with Pepper Sauce

Ingredients (for 4 servings) 450 g (1 lb) lean minced beef 1 egg 25 g (1 oz) fresh breadcrumbs 1 onion, finely chopped salt 2 tbsp green peppercorns 1 tbsp vegetable oil 25 g (1 oz) butter 3 tbsp brandy…