To make the jerk marinade, combine the spring onions, ginger, garlic, onion, scotch bonnet chillies, dried thyme, lime juice, soy sauce, vegetable oil, brown sugar and ground allspice in a food processor along with 1 tsp salt, and blend to a purée. If you’re having trouble getting it to blend, just keep turning off the blender, stirring the mixture, and trying again. Eventually it will start to blend up – don’t be tempted to add water, as you want a thick paste.