For the dressing, mix the vinegar, sugar, olive oil and sliced garlic in a bowl. Leave to sit until needed.
Use a skewer to pierce the aubergines, making sure they are evenly pricked all over. Rub a little olive oil on them and season well with salt.
Place on a barbecue chargrill plate, in a chargrill pan or over a naked gas flame and cook, turning continuously, until the skin is blackened and the aubergine is cooked. Place in a bowl to cool and add any liquid that draws out of the aubergines to the dressing.
Halve the aubergines lengthways and gently peel. Arrange in a serving dish and season well.
Loosely scatter the chilli, parsley, coriander and hazelnut over the aubergine. Dress generously, then finish with the pink peppercorns.