2 medium eggplants, quartered lengthways and cut into 1cm-thick slices
6 large flat mushrooms, stems discarded, cut into sixths
3 small red onions, quartered with root end left intact
¼ cup sesame seeds
¼ teaspoon cayenne pepper
6 x 180g marlin steaks, skin off, trimmed of any bloodline (see notes)
½ cup vegetable oil
3 green onions, finely sliced lengthways

Teriyaki Marinade
½ cup light soy sauce
⅓ cup mirin (see notes)
1 teaspoon castor sugar
1 tablespoon sesame oil
1 tablespoon grated ginger
3 cloves garlic, finely chopped

Make Teriyaki Marinade: combine ingredients and stir well until sugar dissolves.
Place eggplant, mushroom and onion in a shallow tray and pour Teriyaki Marinade over them. Turn to coat, then leave to marinate for 30 minutes.

Combine sesame seeds with cayenne pepper. Brush fish with oil and roll it in the sesame seed mixture to lightly coat both sides, cover and refrigerate (see notes).

Heat a barbecue or char-grill plate.

Brush barbecue with oil. Arrange eggplant, mushrooms and onion on the plate and cook, basting occasionally with the marinade, until they’re well coloured and softening. Remove the steaks from the marinade and cook on the grill for 2-8 minutes each side, depending on thickness, they should be still just pink in the centre.

Divide the vegetables between plates, top with steaks and garnish with green onions.