Rub each potato with a little oil and salt, then wrap in a double layer of foil.
Pour the oil into a bowl and stir in the mint. Add the halloumi and toss until well coated in the minty oil. Wrap each piece in a strip of pepper. Cut four lengths of foil about 1cm wide and wrap one around the middle of each parcel to hold them together. You could use skewers instead, but be careful not to split the cheese.
Heat the barbecue. When the coals glow red, put the potatoes directly on them. Cook for 30 mins, turning halfway. Unwrap a potato and check if it is cooked through. If not, rewrap and cook more, checking every 10 mins. Alternatively, bake in the oven at 200C/180C fan/gas 6 for 50 mins-1 hr.
Meanwhile cook the pepper parcels on the barbecue or a griddle pan for 3-4 mins each side or until the pepper chars and the cheese melts a bit. Remove from the grill and unwind the foil or remove the skewers. Split the potatoes, add butter if you like, then lay a parcel in the centre of each. Add a squeeze of lemon and scatter over some parsley to serve.