Cut the aubergine lengthways into three thick slices, then cut these into evenly sized batons. Sprinkle them with salt, mix well and leave in a colander for at least 30 minutes to drain.

Preheat oven to 180°C. Shake off any excess moisture on the aubergines before using 2 tbsp of oil to lightly coat each baton. Roast in oven for 20-25mins or until golden-brown on the outside

Heat a wok to a medium heat beat adding 3 tbsp of oil. Add the chilli bean paste (and optional black bean sauce) and stir-fry until the oil is red and fragrant, then add the ginger, garlic and dried chillies before stir-frying until you can smell their aromas. Take care not to burn these seasonings; remove the wok from the heat for a few seconds if necessary to control the temperature

Add the stock and add 2 tsp sugar and mix well. Season with salt to taste if necessary and add further sugar to taste. Add the fried eggplant to the sauce and let them simmer gently for a minute or so to absorb some of the flavours.

Then stir the potato flour or cornstarch mixture, pour it over the eggplant and stir in gently to thicken the sauce. Add the vinegar and spring onions and stir a few times, then serve.