- In large saucepan, combine rhubarb and 1 cup sugar, orange peel, orange juice and corn syrup.
- Heat to boiling, stirring constantly.
- Reduce heat and cook until rhubarb is tender, about 10 minutes; cool.
- Pour into loaf pan or freezer trays; freeze to slush consistency, about 1–2 hours.
- Beat egg whites until foamy; gradually add 2 tbsp sugar, beating continuously until stiff peaks form.
- Into large bowl, spoon partially frozen rhubarb mix; beat until light and fluffy.
- Fold in egg whites.
- Return to freezer container; cover with plastic wrap to prevent crystals from forming.
- Freeze until firm, about 3–4 hours, stirring occasionally.
- Allow to soften slightly; spoon into sherbet glasses.
- Garnish with toasted coconut or nuts.