An official meatball recipe, proving you do not need bread crumbs to make a good meatball!
http://flavorsofbrazil.blogspot.com/2012/07/recipe-dona-zenas-meatballs-bola-da.html
2 1/4 lb (1 kg) good quality ground meat – ground chuck is best
1/2 cup ripe tomato, peeled, seeded and finely chopped
1/4 cup onion, peeled, seeded and finely chopped
1/4 cup green bell pepper, seeded and finely chopped
1/4 cup cilantro, leaves only, finely chopped
1 Tbsp garlic, minced
3 Tbsp white wine vinegar
3 Tbsp soy sauce
salt and pepper to taste
neutral vegetable oil for frying