Heat the oil in a large dutch oven or stock pot over medium heat. Add the onion and tomatoes, and cook for 5 minutes, or until the onion begins to soften. Stir in the garlic, jalapeño, ginger, turmeric root, cumin seed, ground turmeric, and garam masala. Cook for another 2 minutes, or until the spices are fragrant, the cumin seeds begin to pop, and the onion is soft and translucent, stirring frequently. Then, stir in the kale and cook for another 2 minutes, or until it just begins to wilt.
Add the filtered water, split peas, and potatoes. Give everything a good stir, increase the heat to medium-high, and bring to a boil for 5 minutes. Then, reduce the heat to medium-low, cover, and simmer for 1 hour, or until the split peas are very tender and beginning to break down into the broth, stirring occasionally.
Season with the sea salt. If desired, stir in another 1 to 1 ½ cups filtered water to thin the curry, and season with more sea salt to taste.
Turn off the heat and stir in the fresh cilantro just before serving. Serve the curry on its own or alongside a mound of basmati rice. If desired, garnish with more cilantro, to taste.