Ingredients:
- 1/2 cup sugar
- 1/4 cup fresh orange juice
- 1 pound rhubarb, trimmed and thickly sliced
- 2 teaspoons finely grated orange zest
- 1 1/2 cups cake flour
- 1 tablespoon baking powder
- Pinch of salt
- 6 qualified eggs at room temperature, separated
- 1 3/4 cups sugar
- 2 tablespoons finely grated orange zest
- 1/3 cup vegetable oil
- 1/2 cup fresh orange juice
- Pinch of cream of tartar