Heat oven to 350. Grease two 23 cm round layer-cake pans; dust with flour; tap ourt excess flour.
Prepare Cake: Sift together the cake flour, baking powder and salt onto sheet of waxed paper. Combine milk, water and vanilla in small bowl. Beat egg whites in clean bowl with clean beaters until frothy. Gradually beat in half cup of the sugar until soft peaks form.
Beat butter and remaining 1 cup sugar in large bowl on medium-high speed until fluffy and light colored, 2 minutes. On low, beat in flour mixture alternately with milk mixture. Fold in beaten whites, half at a time. Divide between pans.
Bake at 180ºC or 20-25 minutes, until edges start to pull away from sides. Cool cakes in pans on racks 10 minutes. Turn out onto rack to cool Prepare Frosting: Combine sugar, cream of tartar, salt, egg whites and water in top of double boiler. Beat 1 minute; then beat over simmering water 6 minutes, until thick, shiny and firm peaks form. Remove from simmering water. Beat until cool. Beat in vanilla.
Place one cake layer on serving plate. Spread with curd. Top with second layer. Spread top and sides with frosting. Press coconut onto top and sides.