Preheat the oven to 200°C/400°F/gas mark 6.
Cut the aubergines lengthways in quarters, then slice each quarter inch into 1-inch chunks. Drizzle the chunks in the olive oil, sprinkle with salt, and place on a baking tray in the oven for 20-30 minutes (or until soft and brown), turning the halfway through cooking.
Half the peppers lengthways, remove the seeds and pith, brush lightly with olive oil and place side down in oven for 30 minutes or until skins have charred. Once cooked, remove from oven, allow to cool and slice into small strips.
Meanwhile, place the lentils in a saucepan with plenty of cold water, the onion halves and the bay leaves. Bring to the boil and reduce to simmer until lentils are soft (approx. 30 minutes). You may need to add more water throughout the process. Once cooked, strain the lentils through a sieve and rinse with cold water, discarding the onion and bay leaves.
Mix all the dressing ingredients together in a jar until combined.
Mix everything together in a serving bowl, leave to stand for 30 minutes, and serve. Note this salad is best served at room temperature.