This simple coconut custard-filled pie would make a sweet ending to a hearty dinner.
Make the crust: In a large bowl, combine flour and salt. Cut margarine and butter into small pieces and add to bowl. Working quickly using a knife or pastry blender, cut flour and fat together until mixture resembles a coarse meal. Sprinkle water over surface, mixing it quickly just until dough forms a smooth ball. Flatten dough into a disc. Refrigerate for at least 30 minutes.
Preheat oven to 400 degrees. Roll one piece chilled dough on a floured surface to a thickness of 1/8 inch and fit it into a 9-inch pie pan (refrigerate the other piece of pastry for another occasion). Fold over edges and pinch all around. Line pastry with parchment paper and weigh it down with dried beans or pebbles. Blind-bake for 20 minutes.
Remove paper and weights. Return crust to oven to bake for 5 more minutes or until light golden-brown.
Make the filling: In a bowl that will fit over a pan of boiling water (or in a double boiler), combine the flour, 1/2 cup sugar, and 1/8 teaspoon salt. Heat milk in a heavy saucepan over medium-high heat until small bubbles appear at the edges. Using a whisk to stir, pour scalded milk into flour mixture and cook over medium heat until it thickens, 3-4 minutes.
In a large bowl, whisk together egg yolks and add 1/2 cup hot custard mixture. Whisk egg yolk mixture back into custard (still on the stove top). Blend in butter and vanilla. Cook 6 minutes more. Remove from heat. Fold in 1 cup coconut.
Spoon custard filling into the cooked piecrust. Smooth it out evenly. Chill thoroughly, until set.
In a large bowl, whip egg whites until stiff. Add superfine sugar, pinch of salt, and 1/8 teaspoon cream of tartar and continue to whip for 2 minutes until glossy and stiff peaks are formed.
Spread meringue over filling. Torch with kitchen blow torch or broil until meringue is lightly browned.