1. Preheat oven to 350 degrees F and grease a casserole dish. Boil yams until barely tender (whole or cut width wise, in big pieces). Peel. Cool.
2. Slice and alternate yams and peeled apple rings in prepared casserole dish.
3. Boil vegan sugar, water, margarine, cornstarch and salt, until it begins to thicken.
4. Pour over yams and apples and bake, covered for 1 hour.
Source: Recipe is from my mom-in-law.