Combine all sauce ingredients and mix in blender or food processor with metal blade.Pour into a 4-qt ovenproof stewing pot and let simmer over medium heat while you prepare the cabbage balls.
Core the cabbage. Pull off as many leaves as possible til they become too small to hold filling. Bring 1 cup of water to a boil, place the leaves in the water, cover, turn to simmer, and let cook for 10 minutes til soft, or microwave with 1/4 cup water on HIGH for 6 minutes. Drain.
Combine ground beef, grated potato, chopped onion, eggs, ketchup, matzo meal (or bread crumbs) and 1/2 cup water. Mix well. Season with salt and pepper.
Fill the cabbage leaves by placing about 1 tablespoon of the ground meat mixture in the middle of each leaf. Fold over the sides and roll the cabbage ball away from you.
Place seam side down in the simmering sauce. Continue til all the cabbage leaves have been used. (If you have some ground beef balls left over, just add them to the sauce.)
Cut up remaining small pieces of cabbage and distribute them evenly over the top of the balls. Add the bay leaf. Check for seasonings. (You may wish to add more lemon juice, cranberry sauce or brown sugar, according to your taste.)
Simmer, covered on top of the stove for 20 minutes.
OVEN: 350 Bake uncovered for 20 minutes more to brown the top.