Heat a little vegetable oil in a large pan and gently saute onion until softish. Then remove onion and wipe out the pan.
To make the Jerk sauce, mix together green onions, 2 teaspoons sambel, soy, tomato ketchup, sugar, 1/4 cup vegetable oil, allspice, ground coriander and garlic in a food processor. Then taste for seasoning and transfer to a bowl.
Place pork mince and sausage meat in another bowl and mix together with some of the Jerk mixture, 1 teaspoons sambel and salt and pepper.
Form the mixture into patties and panfry in a thin layer of hot vegetable oil. Then drain on kitchen paper towels.
To make the mayonnaise, mix together mayonnaise, 2 heaped teaspoons sambel and sweet chilli sauce. Set aside.
Gently toss the salad leaves with balsamic and olive oil to taste.
To serve, smear the mayonnaise on the base of burger buns and top with sliced tomato, a mound of dressed lettuce, onions, 1 or 2 burgers patties, Jerk sauce and then the bun lids.