1. After draining sweet potatoes place them in a baking dish.
2. Cover potatoes with orange juice.
3. In a large mixing bowl mix together flour, sugar, cinnamon and salt.
4. Cut margarine into mixture with a pastry blender.
5. Place crumbly mixture over top of potatoes.
6. Preheat oven to 350 degrees.
7. Bake 30 minutes.
8. Place marshmallows on top.
9. Broil just until marshmallows start to brown.