Preheat the oven to 190°C, fan 170°C, Gas Mark 5.
Mix together the ketchup, sugar, soy sauce and mustard and pour into a roasting tin. Add 4 pork sausages and toss in the mixture until fully coated. Roast for 30 minutes, turning the sausages once or twice during the cooking time.
Warm up 4 rolls in the oven for 3 minutes. Remove and cut them in half, leaving one side attached. Place one sausage in each roll, along with some salad leaves and a dollop of sweetcorn relish.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home and view the full Food safety at home video.