Heat the oven to180 degrees celcius. Toss the eggplant in the olive oil and season with a little salt. Place on a baking tray lined with baking paper and roast for 20 minutes, or until the eggplant is slightly browned. If you like, you can salt and rinse the eggplants first, but its not really necessary as the bitterness in the eggplant works well with the sweet miso.
Meanwhile, mix together the miso dressing ingredients and pour over the roasted eggplant, tossing it on the tray to coat well. Continue to roast for a further 10 minutes, or until the miso sauce starts to caramelise.
Remove the eggplant from the oven, transfer to a serving plate, scatter with spring onion and toasted sesame seeds, and top with tahini and serve.