In a bowl, whisk together flour, sugar, cream of tartar and baking soda.
Add the coconut milk, water, coconut oil, and vanilla extract. Whisk gently until just combined. The batter should be thick but pourable; some small lumps are okay. If it’s too stiff, add water 1 tablespoon at a time, taking care not to overmix.
Heat a cast-iron skillet or griddle over medium heat and lightly coat with coconut oil. Pour about ¼ cup batter for each pancake, leaving space between them. Cook until the bottoms are golden and bubbles form on the surface, about 2–4 minutes. Flip and cook for another 1–2 minutes, until golden brown.
Serve 2 pancakes per person, topped with pineapple, coconut flakes, and a drizzle of maple syrup if desired.