Preheat the oven at 180°C.
Combine the flour, desiccated coconut, baking powder, baking soda, salt and turmeric powder in a large bowl. Run a whisk through the ingredients or pass through a sieve.
In a medium bowl, rub the lemon zest along with the sugar with your fingertips, until you get a nice citrussy aroma. Add the lemon juice, coconut oil, yogurt and egg into the sugar, along with 2-3 tablespoons of water. Using an electric whisk, beat on medium speed for 2-3 minutes. Tip: Ensuring all ingredients are at room temperature is ideal or the coconut oil may turn into slightly solidified bits. No harm done, it will all get incorporated when you beat in the flour.
Coat the bottom and sides of a regular loaf tin (9 X 5.5 inches) with 1-2 teaspoons of soft butter.
Scrape out the prepared batter into the loaf tin and smoothen out the top with a spatula.
Arrange a few lemon slices on the top and sprinkle some desiccated coconut all over.
Bake in the preheated oven at 180C for 30 minutes. If you are using a narrower loaf tin, the cake will have more height in which cake bake for a while longer until a tester comes out clean.
Once the cake is out of the oven, in a small cup combine the icing sugar with juice of half a lemon. Pour this drizzle into the crevices of the cake.
Wait for 5-7 minutes to unmold the cake. Cool on a wire rack for 15-20 minutes and cut into slices of desired thickness.