Prick the aubergines all over with a fork, then place directly over a gas flame or under the grill of the oven (on high heat), and char, turning, for about 5-10 mins or until they feel like they are collapsing inside. Remove and leave to cool.
Once the aubergine has cooled, split them in half and carefully scoop out the juicy, soft flesh into a bowl. Peel it away from the burned skin, being careful to capture any of the juices that escape onto the board. Roughly chop the flesh and set aside.
Heat the olive oil in a pan over a medium to high heat, add the onion, bay leaf and a pinch of salt and cook, stirring, for about 10 mins, until the onion is softening and just starting to colour. Add the garlic and chilli and cook for a couple of mins more. Mix in the tomatoes and red wine vinegar, and cook, stirring, for about 10 mins until they are collapsing. Add the aubergine, and mix well with the other ingredients, cooking for a few more mins, then add the lentils and 100ml water. Continue to cook until most of the water has reduced. Season.
Serve the warm ragu on top of a generous serving of swede or parsnip puree, polenta, butterbean mash, or hummus. Garnish with the walnuts and parsley.