Step 1 Spray a medium saucepan with oil and place over medium-high heat. Add onion, celery and carrot. Cook, stirring, for 5 minutes, until soft. Add garlic and thyme and cook for another minute.

Step 2 Add lentils, beans, zucchini, tomatoes, stock and vinegar and bring to the boil. Reduce heat and simmer, covered, for 20 minutes. Spoon into an 8 cup-capacity ovenproof dish.

Step 3 Preheat oven to 200°C. Place potatoes into a microwave-safe bowl and cover with cling wrap. Microwave on high for 7 minutes, or until very tender. Drain, then mash with milk. Spoon evenly over vegie mixture, then sprinkle with parmesan. Bake for 15–20 minutes, or until golden.