Peel the onions, and chop them into ½-inch pieces. Finely mince the garlic (or use a garlic press). Heat the tablespoon of coconut oil in a large cast-iron or non-stick skillet over medium heat.
While the onions cook, peel and chop the potatoes and sweet potato. Once the onions are beginning to soften and become translucent, add the garlic. Cook, stirring often, until the garlic is fragrant, then add the potatoes, sweet potato, broth, curry powder and salt. Raise the heat under the skillet to medium-high and bring the broth to a simmer. Cook the curried mixture until the potatoes/sweet potatoes are soft and the broth has mostly boiled off. The texture should be thick and sticky.
Add the tomato paste, chopped tomatoes and chopped chard. Stir to thoroughly combine, then allow to cook until the chard is wilted and the tomatoes are softened. Remove from the heat and transfer to a pie plate/pan.
To make the purple sweet potato topping, cook the large purple sweet potato, wrapped in a damp paper towel, on high in the microwave for 8-12 minutes until very soft when pierced with a fork. Remove to a plate, and allow to cool enough to touch. Gently work the skin off of the sweet potato, then transfer it to a bowl and add salt to taste. Mash with a fork (or use a hand mixer, if you intend to use a frosting tip) then spread over the top of the filling. Finish with a sprinkle of red chili flakes and fresh parsley.