Set up your barbecue for the heat canyon technique by placing coals on opposite sides of the barbecue to make two heat walls - this will create sections of hot, direct heat on the sides, with an indirect, cooler area in the middle to ensure your meat gets consistent heat throughout the cook. Cover with the lid and allow to heat up like an outdoor oven – you want a temperature of around 175°C/345°F.
Rub the sweet potatoes all over with a drizzle of oil and a good pinch of salt. Place on the middle of the barbecue, cover with the lid and bake for around 1 hour, or until soft in the middle and crisp on the outside. Meanwhile, fry the bacon (if using) in a pan over a high heat (you can do this on the hob) until golden and crisp, then set aside for later.
Split the potatoes open, crumble in the bacon (if using) and grate over the cheese. Return to the indirect heat on the barbecue for a further 5 to 10 minutes with the lid on, or until the cheese has melted. Finely slice the spring onions and chilli then sprinkle them over the potatoes, serve with spoonfuls of soured cream and devour.