Beat egg whites with salt until soft peaks form. Gradually beat in ¼ cup sugar until stiff peaks form. Without washing beater, beat egg yolks until thickened and lemon color, gradually beat in ¼ cup sugar, flour, butter, orange rind, orange juice, and lemon juice. Gradually beat in milk until smooth, fold in egg whites. Turn into 6 (6-ounce) custard cups. Place in pan of hot water that comes about as high as pudding mixture. Bake in preheated 350°F oven until knife inserted in center comes out clean, about 35 minutes. Chill overnight. Bottom will be a sauce, top cake-like.
Source: Diana Baker Woodall