1. Boil yam until nearly done, not too mushy, 7-10 minutes. Combine peanut butter, soy sauce, vinegar, cumin and sesame seed oil in a small bowl, set aside.
2. Once the yam is cooked as much as you like, drain. Add carrots to a large frying pan or a wok and cook for just a few minutes. Add sweet potatoes and chiles.
3. Cook for a couple more minutes. Add peanut butter mixture and stir until well mixed. Add tomatoes and mix. Add the orange juice at the last minute to sort of deglaze the pan. Remove from heat and mix in raisins.
This was one of those recipes I made up in the grocery store as I walked through the aisles, and it turned out pretty well, I think. It's good and spicy.