Leave the stems on and pierce each eggplant all over with a bamboo skewer or fork, about 10 holes each, so they don't burst.
Grill the eggplant whole on the rack of a fish grill for about 5 minutes, turn, and grill another 3 minutes, until the skin is blackened and wrinkled and the flesh gives completely when pressed. No fish grill: broil on high for 10-15 minutes turning a few times, or char over a gas burner flame with tongs.
While still hot, slide a skewer or the back of a knife between the skin and flesh and pull the skin away in strips. Discard the skin. Hold the stem with a folded paper towel if it's too hot.
Trim off the stem and cut the eggplant into bite-size pieces, or tear it lengthwise into strips.
Pile into a small bowl, top with bonito flakes, and pour over ponzu or soy sauce just before eating. Add grated ginger if using soy sauce. Good warm, or chilled in the fridge for an hour.