2 large chipping potatoes, cut into fine matchsticks
For the homemade tomato ketchup, heat the vinegar, spices and sugar in a heavy-based saucepan until simmering.
Add the remaining ingredients, except the corn flour, bring to the boil and stir to prevent the mixture from sticking to the side of the pan. Once the mixture has reached boiling point, reduce the temperature to a simmer and cook for a further 6-8 minutes, stirring occasionally.
Blend the mixture in a blender until smooth, then push the ketchup through a sieve into a bowl.
If the mixture is a little thin, whisk the corn flour mixture into the ketchup and heat until the mixture has thickened. Season with salt and freshly ground black pepper.
Cook the corn on the cob in a pan of boiling water for 6-8 minutes.
Drain and return to the pan with the butter then season with salt and freshly ground black pepper. Keep warm.
For the beefburgers, heat the oil in a frying pan, then fry the shallot for 2-3 minutes, or until softened. Remove the pan from the heat and set aside to cool slightly.
Place the beef mince, cooked shallot and flatleaf parsley, in a large bowl and mix until well combined. Season to taste with salt and freshly ground black pepper. Divide the mixture into four and shape into burgers.
Reheat the frying pan used to cook the shallots until hot, and fry the burgers for 4-6 minutes on each side, or until just cooked through. Remove from the pan and set to rest in a warm place for 2-3 minutes.
For the onion rings and chips, heat the vegetable oil in a deep-fat fryer to 190C/375F.
Sprinkle the flour and breadcrumbs onto separate plates. Whisk the egg in a bowl.
Dredge the shallot rings in the flour, dip into the egg and coat in the breadcrumbs.
Deep-fry the onion rings for 1-2 minutes, or until crisp and golden-brown. Remove from the pan with a slotted spoon and set aside to drain on kitchen paper. Season with a little salt.
Add the potatoes to the deep-fat fryer and fry for 3-4 minutes, or until golden-brown and crisp. Remove from the pan with a slotted spoon and set aside to drain on kitchen paper. Season with a little salt.
Meanwhile, toast the burger buns, cut side-down, in a hot frying pan for one minute, or until hot.
To serve, place the bottom of the buns onto serving plates, then top with some lettuce and tomato, a burger, a slice of mozzarella and some shallot rings. Cover with the top of the burger bun and pile some fries alongside. Serve with a piece of corn on the cob and a dollop of ketchup.