Make the chilli: Heat oil in a saucepan over medium heat. Sweat the onion for 4-5 minutes until soft. Add garlic and fry for another minute. Add cumin seeds and stir for 1-2 minutes until aromatic, then mix in the chilli powder. Season the mince, turn up the heat, add more oil, and fry for 6-8 minutes until browned. Add Worcestershire sauce, turn down the heat, and stir in tomato puree for 1-2 minutes. Add tomatoes, sugar, and oregano. Cover and simmer for 20 minutes, stirring frequently.
Caramelise the onions: Heat a small frying pan with a dash of oil over medium-low heat. Add the red onions with a pinch of salt and sweat gently for 10-15 minutes until completely soft and golden. Do not increase the heat. Add the sugar and balsamic vinegar, increase heat to medium, and cook for about 5 minutes until sticky and reduced.
Cook the sausages: Boil or griddle the frankfurters for 6 minutes until heated through. Drain.
Assemble: Divide the caramelised onions between the opened hotdog buns. Top with the cooked sausage and a generous spoonful or two of chilli. Crumble over the Lancashire cheese and finish with chopped spring onion.
