If you are marinading the meat mix together the ponzu and mirin and marinate the meat for an hour, turning at least once. Then remove from the marinade and discard the marinade.
Season the meat and cook on a hot griddle until the fat is golden and the meat is crisp on both sides. Remove from the grill and leave to rest for 5 minutes.
Toast the sesame seeds in a dry pan over a moderate heat until golden. Mix the ponzu, mirin, dark soy, toasted sesame seeds and a dash of sesame oil.
Slice the pork thickly into pieces about the width of your little finger and put into the marinade, turning a couple of times. Pour any cooking juices into the marinade.
Slice the white mooli into wafer this slices and halve the radishes. Toss the radishes together with the salad leaves and divide between two shallow bowls.
Divide the pork between the bowls and spoon over the dressing, then serve.