Something as simple as an onion can be transformed when cooked over open flames.
4 large red onions, peeled, cut into 1cm-thick slices
2tbsp mirin (Japanese sweet rice wine)
4tbsp sweet soy
1tbsp ponzu (Japanese, citrus-based sauce)
Cook the onion slices for about 7-8 minutes on each side on the medium heat of the barbecue. Meanwhile mix the mirin, sweet soy and ponzu together. Arrange the onions on a serving dish and spoon over the sauce. Garnish with fresh herbs.