Combine 1 cup sugar, cornstarch, and salt in top of a nonaluminum double boiler. Gradually add orange juice, water, lemon juice, and egg yolks; stir until smooth. Cook over boiling water, stirring constantly, until thickened and smooth. Remove from heat; stir in orange rind, butter, and food coloring, mixing well. Spoon filling into prepared tart shells.
Beat egg whites (at room temperature) until foamy. Gradually add 1/4 cup plus 2 tablespoons sugar, 1 tablespoon at a time, beating until stiff peaks form. Spread 1 tablespoon meringue over each tart, sealing to edge of pastry. Bake at 350° for 10 to 12 minutes or until meringue is golden brown. Cool tarts to room temperature; chill.