Steam or boil the potato cubes until they are tender but still retain their shape. In a large skillet with a cover, heat up 3 tablespoons olive oil, over medium-high heat. Add the mustard seeds and when they start to pop, add the cumin seeds and the curry leaves. Let cook 1 minute. Add the onion and sauté for 2 minutes. Add the turmeric, mix well, cover and cook until the onion is well browned, about 8-10 minutes. Remove to a small bowl and set aside. Add the last 3 tablespoons of oil to the same skillet and increase the heat slightly. Add the cauliflower and sprinkle generously with sea salt. Sauté while stirring until the cauliflower starts to take on some color, 6-7 minutes. Return the onion to the skillet and lower the heat to medium-high. Add the garlic-ginger paste and the potatoes and cook for 2 minutes. Add the spinach, carrot and 1/2 cup water. Cover and cook until the spinach is wilted, about 2 minutes. Uncover, add the lime juice and garam masala and stir well. Remove to a serving platter, garnish with cilantro and serve. Bon appétit!