Preheat oven to 200°C/180°fan/Gas 6. Cut aubergine into four slices, lengthways, then score the flesh in a criss-cross pattern. Place in a roasting tin in a single layer.
In a small bowl, mix together miso, maple syrup and sesame oil. Spoon two-thirds over aubergine slices. Bake for 10 minutes.
Turn up heat to 220°C/200°fan/Gas 7. Spoon remaining miso mixture over aubergine and sprinkle with sesame seeds and nuts. Bake for a further 10 minutes or until tender.
Scatter over mint to serve, if you like.