Heat the vegetable oil in a large skillet over medium heat.
Add the chopped onion and garlic, and sauté until the onion is translucent and fragrant.
Add the chopped spinach or cassava leaves and cook until wilted.
Stir in the coconut milk, ground coriander, and ground cumin. Cook for an additional 5 minutes, allowing the mixture to thicken slightly.
Season with salt and black pepper to taste. Remove from heat and let the filling cool.
In a large bowl, combine the flour and salt.
Cut in the chilled butter until the mixture resembles coarse crumbs.
Gradually add the cold water, mixing until a dough forms. Knead lightly until smooth.
Divide the dough into small balls and roll each ball into a thin circle on a floured surface.
Spoon a portion of the cooled filling onto the center of each dough circle.
Fold the dough over the filling to create a half-moon shape, pressing the edges together to seal.
Heat a little oil in a skillet over medium heat.
Cook the mataba on each side for 3-4 minutes, or until golden brown and crispy.
Enjoy your meal!