Finely chop in a food processor or with a knife: onion, parsley and garlic, move into a large bowl. Process the potato into a mash in a food processor or on a grater. Squeeze out the juice and add the mash to the bowl. Add the meat, chili, egg, cumin, salt and olive oil, and mix well. Set aside for an hour.
Heat some olive oil in a large cooking pot. Add a chopped garlic clove and fry for a minute. Add a chopped chili. After a minute add crushed tomatoes, cumin, salt, chopped bell pepper, mix well and cook for a few more minutes. Add a cup of water and stir. When the sauce boils, lower the heat and cook for five more minutes. Meanwhile, with wet hands, make the meatballs. When the sauce is ready carefully put the meatballs in the pot, so they will be covered with it. Cook until the meatballs are done. Serve hot.