In a food processor, grind walnuts until a coarse to fine meal. Remove to a bowl.
Rinse out food processor bowl, and grind both onions to a coarse puree. Separate the onions into two equal portions.
In a large bowl, combine ground beef one portion of ground onion, turmeric, cinnamon, garlic powder, salt and pepper. Using your hands blend together.
Using your hands, roll ground beef mixture into about 1 1/2 inch balls and place in a large frying pan. Cook meatballs until they are light brown on all sides.**
Transfer browned meatballs to a large pot. Add to the pot, the second portion of the ground onion, ground walnuts and 3 cups water. Bring to a boil. Reduce heat. Simmer, stirring occasionally, for one hour (leave lid half on, so that steam can escape).
This is a good time to prepare rice, according to package directions.
After one hour of simmering the meatballs, walnuts and onion, add pomegranate molasses and sugar. Simmer, stirring occasionally, for one more hour (with lid half on).
Stew will thicken and darken as it cooks. You can add more water if you like it thinner or soupier. When you remove stew from the heat, it will thicken further.
Pour cooked rice onto a large serving plate, or into a large serving bowl. Top rice with saffron water.
Pour meatball stew into a second large bowl.
Serve rice and stew alongside one another.