Split the eggplants lengthwise. Score the cut sides.
Toss the eggplants and bell peppers in oil.
Grill the eggplants, about three minutes per side.
Grill the bell peppers until the skins are charred (see notes after the recipe).
While the eggplants and bell peppers cool, prepare the rest of the rest of the vegetables. Halve the tomatoes, scoop out the seeds and discard. Dice the tomatoes.
Peel and roughly chop the red onion.
Make the dressing by stirring together all the ingredients.
When the eggplants are cool enough to handle, scoop out the flesh and roughly chop.
Using a kitchen towel or a paper towel, wipe the bell peppers to remove the skins (or peel off if that’s more convenient for you).
Cut the peeled bell peppers in half and scrape off the seeds. Dice the grilled bell peppers.
In a large bowl, toss the eggplants, bell peppers, onion and tomatoes lightly but thoroughly.
Drizzle in about three tablespoonfuls of the sesame-soy dressing and toss again.
Serve the grilled eggplant and bell pepper salad with the remaining dressing on the side.
Optionally, garnish the salad with chiffonaded Thai basil.