Heat Dutch oven over medium heat. Add curry powder, garam masala and mustard seeds and toast, stirring, until spices begin to darken, about 1 minute. Transfer to small bowl.
Add oil, onion, garlic, ginger and salt to the pot and cook, stirring, until softened, 3 to 4 minutes. Stir in eggplant, cauliflower, tomatoes, chickpeas, water and reserved spices. Bring to simmer. Cover, reduce heat and cook, stirring occasionally, until vegetables are tender, 15 to 20 minutes. Top each serving with a dollop of yogurt and a sprinkling of cilantro, if desired.