4 medium King Edward or Lincolnshire potatoes, cut into 2cm/¾in cubes
1 handful fresh flatleaf parsley, roughly chopped
1 banana shallot, finely chopped
salt and freshly ground black pepper
2 tbsp olive oil
10g/½oz unsalted butter
65g/2¼oz unsalted butter
4 x 225g/8oz sirloin steaks (preferably organic), 2cm/¾in thick