Coconut lemon fillng

1. x cornstarch combine 2 cups water, lemon juice, salt, and 1 cup sugar in top of double boiler and bring to a boil over direct heat.
2. Place over boiling water.
3. Add 1 cup water gradually to flour, mixing to a smooth paste.
4. Add gradually to hot mixture and cook 5 minutes, stirring constantly.
5. Beat egg yolks with ½ cup sugar; add slowly to lemon mixture, cook 2 minutes, stirring constantly.
6. Add lemon rind and butter.
7. Cool 10 minutes.
8. Makes 4-2/3 cups filling, or enough to spread between layers and on top and sides of three 9-inch layers.
9. Sprinkle coconut generously on sides of cake.
10. Decorate top of cake with a 1-inch border of coconut.