The addition of some belly pork to the basic mix really adds a moistness and richness to the burger. The plum relish is a must! It may be kept refrigerated for up to a week.
Place both pork minces in a bowl, add the remaining burger ingredients and bring the mix together. Place all the ingredients for the baste in a bowl and mix well. Add 2 tbsp of the baste to the burger mix, mix well, taking care not to overwork. Place in the refrigerator, covered, for 1 hour.
Heat a chargrill or pan grill until very hot. Brush the grill with a l