Step 1 Heat half the olive oil in a large, deep non-stick saucepan (with a lid) set over medium heat. Add onion, garlic, carrots and celery; cook, stirring, for 5 minutes, or until soft. Add spices and stir for 1 minute, or until fragrant.
Step 2 Add tomatoes to saucepan and bring to the boil. Reduce heat, cover pan and simmer for 20 minutes; uncover, add lentils and simmer for 15 minutes.
Step 3 Meanwhile, preheat oven to 180°C. Line a large baking tray with baking paper. Lay eggplant slices on tray in a single layer and spray with olive oil; bake for 15–20 minutes, or until tender.
Step 4 Place potatoes in a medium saucepan of water and bring to the boil; boil for 15 minutes, or until tender, then drain and cut into 5mm-thick slices.
Step 5 Spread 1/2 cup of lentil mixture across base of a 3-litre (12-cup) capacity ovenproof dish. Arrange half the eggplant slices over lentil mixture. Top eggplant with half the remaining lentil mixture, then top with remaining eggplant and remaining lentil mixture. Arrange potato slices over lentil mixture and scatter with parmesan. Put dish in oven to bake, uncovered, for 45 minutes, or until tender and golden. Leave moussaka to stand for about 15 minutes.
Step 6 Toss salad leaves with balsamic vinegar and remaining olive oil. Serve moussaka with salad.