In a large (oven-safe) pot, heat cooking oil over medium heat (I used my Dutch oven for this). Add onions and cook for 2-3 minutes. Then add garlic, ginger, fresh turmeric (if using), and bell pepper. Cook for 2 minutes more. Stir regularly.
Stir in eggplant and cook for 5 minutes more.
Then add tomatoes, water, and lentils. Give it a good stir, cover and simmer for 30-40 minutes or until beans/lentils are soft. Stir occasionally. Add water if needed. Season with salt and pepper to taste. Last 5 minutes, add spinach.
Meanwhile, heat a pot of water. Cook potatoes and carrots until tender. Drain and mash when ready, season with nutmeg, black pepper, and sea salt to taste. Add a little water or milk if needed.
If you used a normal cooking pot, add lentil stew to an oven-safe dish first, then top with carrot mash. Add panko on top and grill in the oven for 10 minutes or until slightly browned.