Preheat oven to 400. Line a baking sheet with parchment paper.
In a mixing bowl, stir together the flour, sugar, coconut, baking powder, baking soda, and salt. Cut in the butter using a pastry blender until the mixture is crumbly.
In a smaller bowl, whisk together the yogurt, egg yolk, vanilla, coconut extract, and lime zest. Add the yogurt mixture into the flour/butter mixture and gently fold it in, forming a shaggy dough. Turn the dough out onto a lightly floured work surface. Gently pat the dough together until it holds its shape and can be formed into a 3/4 inch-thick disc, being careful not to overwork the dough or knead it too much. Cut the disc into 8 equal triangles. Place each triangle on the parchment-lined baking sheet. Brush the top of each triangle with heavy cream. Bake 14-16 minutes or until golden on the edges and cooked through. Set aside to cool on a baking rack while you make the glaze.
!To make Glaze:
Whisk together the Greek yogurt, lime juice, and green food coloring, if using. Gradually add powdered sugar, whisking briskly until smooth, until you have a thick, but runny glaze. Drizzle the glaze over warm scones, then immediately sprinkle scones with toasted coconut. Allow the glaze to set before serving.