Peel and grate the ginger. Wash and finely chop the spring onions. Sprinkle the tuna slices with the chopped spring onions and ginger. Mix honey, balsamic vinegar, soy sauce, sesame oil, chili paste and ground coriander into a marinade and pour over the fish. Cover and marinate for about 1 to 2 hours.
Heat a grill pan. Take the fish out of the marinade and let it drain a little. Put the tuna in the pan and sear it on both sides, then cook on a low heat for 5 minutes, depending on the thickness of the fish slices. Now take the tuna out of the pan and keep it warm.
Pour the marinade into the hot pan, reduce it a little and season with a pinch of salt if necessary. Arrange the tuna slices on plates. Pour the honey soy sauce over them.