Preheat the oven to 350°F (175°C). Lightly grease two 8-inch (20cm) round cake pans with a little oil, then line them with baking paper.
In a large bowl, combine room-temperature milk, water, lemon juice, and yogurt. Let sit for a few minutes to curdle slightly.
Add oil and sugar to the bowl and whisk until smooth and the sugar dissolves. Stir in vanilla extract and desiccated coconut until well combined.
Sift flour, corn starch, baking powder, baking soda, and salt into the bowl. Gently mix until smooth and lump-free; don’t overmix.
Pour the batter into prepared pans, smooth the tops, and bake for 25–30 minutes, until set and springy to the touch.
Cool the cakes in the pans for 10 minutes, then transfer to a wire rack to cool completely. Level the tops with a serrated knife before frosting.