Place flour, coconut, icing sugar and butter in a food processor. Pulse until mixture resembles breadcrumbs. Add egg yolks and continue mixing until dough just comes together. Remove to a floured surface and form dough into a smooth ball. Cover and refrigerate for at least 30 minutes.
Pre-heat oven to 200°C (180°C fan-forced). Roll pastry out on a lightly floured surface to a 6mm thickness to fit a 22cm pie tin (or a fluted tin with removable base). Press into pan, trimming edges and line with paper. Fill with baking beans and blind bake for 10 minutes on an oven tray. Remove paper and baking beans and cook for a further 10 minutes. Allow to cool.
For the filling, combine sugar, tapioca, water and orange juice in a saucepan. Whisk well and heat until boiling and thickened, taking care it does not stick. Remove from heat and whisk in the egg yolks, butter and orange rind until butter is melted. Pour into pastry case and chill for 2-3 hours until set.
For meringue, combine sugar and water in a saucepan. Heat until sugar has dissolved, then continue cooking a further 5 minutes over low heat or until it has reached a temperature of 115°C.
Beat egg whites and cream of tartar until soft peaks form, gradually add hot sugar mixture in a thin steady stream, mixing until thick and glossy and bowl feels cool. Fold in coconut and chill.
For serving, spoon meringue over top of tart and scorch with a blowtorch until golden.