Back in the late '60s, when I went to community college, I made friends with several students from Afghanistan and Iran, who were away from home for the first time and trying to fill their stomachs on a budget and battle homesickness at the same time. This is one of their main dishes, which can feed a small army with less than 2 lbs. of ground meat, a bunch of potatoes, and some rice. It is surprisingly tasty.
Fill large pan or Dutch oven with about 6 cups of water, to start; you can always add more if you need it. Add ketchup, and bring to boil; turn down heat to avoid splashing.
Beat egg slightly, mix together with meat, onion, and spices. Mix with hands, and form meatballs. They will be soft and a little gooey, thanks to the egg, but don't worry. Drop meatballs, as you form them, into ketchup water. Turn heat down to simmer.
As the water sets the meatballs, cut the potatoes into medium-sized chunks (you can leave the skin on, if you want). Gently add these to the water. Cover pot, and simmer for about an hour. The longer this cooks, the better it tastes, and it makes great leftovers. Afghans, I'm told, tend to boil their meat, since the ovens they use for baking produces heat that is unreliable for killing all the harmful bacteria in meat.
Serve over plain white or brown rice. This dish can also be made using chicken parts (dark meat is best) by eliminating the egg, slicing the onion, and first browning the chicken & onion lightly in olive oil before adding to the water. Add the spices to the water.