Helen'S Sweet Potato Casserole

Ingredients:
- 2 Tbsp. flour
- 1/2 c. brown sugar
- 1/2 tsp. salt
- 1 Tbsp. vinegar
- 2 Tbsp. fresh lemon juice
- 1/2 c. fresh orange juice
- 1 Tbsp. grated orange peel
- 2 Tbsp. butter, melted
- 4 cans large whole yams

Directions:
- Melt butter.
- Add flour and stir to cream.
- Add rest of ingredients, except sweet potatoes.
- Boil and simmer for 5 minutes.
- Stir as it thickens and smooths.
- Drain sweet potatoes and lay in 9 x 12-inch pan.
- Pour sauce over potatoes.
- Bake at 300° for 30 minutes.
- Decorate with mandarin oranges and marshmallows.
- Bake again for 5 minutes.