How to make meatballs: you will need ground meat, salt, and any grain product. Eggs and onions are desirable, but optional. The following is more an explanation than a recipe.
Any ground meat will make great meatballs. Dark and white turkey, chicken, beef, buffalo, lamb, and combinations of the above. Leaner meats make more flavorful meatballs. Meatballs, unlike hamburgers, don't get dry with unsufficient fat. I don't cook with pork, but you can make pork meatballs as well. I'd suggest mixing the pork with leaner, tougher meat. A pound of ground meat makes enough meatballs for a dinner for a family of five, and just enough meatballs to use the whole surface of an 12" skillet. It takes less then ten minutes to mix (searching in cupboards not included) and fifteen minutes to fry. You can simmer meatballs in a sauce after that.
Grain product: my mother used to soak stale bread in water for an hour to make the carbohydrate filling. I do, too, when I have some. When I don't, I use oat bran, crumbled matzo, flour, semolina, rice (for slow-cooked meatballs), and ground potato. Leftover mashed potato or cooked rice will work, too. It's totally possible to make no-carb meatballs, but believe me, it's not worth it. Meatballs allow an opportunity to enrich and attune the taste and texture of ground meat; if you didn't care for this opportunity, you would cook hamburgers. Oat bran has a lowest carb/protein ratio, and gives meatballs very even and tender texture. Soaked stale bread is my favorite, but crumbled matzo fits turkey or chicken best.
Eggs: it is best to use just egg whites, slightly whipped. That makes truly delicious, airy meatballs. Whole eggs are much faster to use, and the difference is not that significant. With no eggs, you'll have to mix and work the mixture a bit longer, or meatballs will fall apart on the frying pan.
Onion: I said it's optional, but I strongly suggest using it, unless you hate onions. Onion makes for moister, more flavorful meatballs -- and it's not the onion flavor.
To make a meatball dinner: put a pound of ground meat in a medium or large bowl. Add pre-soaked and sponged out bread (between a fist-size and two fist-size piece), or a cup of any other filing. Finely chop a medium to large yellow onion or, better, grate it on a large grater. You can use any kind of onion here, but anything fancy will be lost. You can substitute onion with grated white or green cabbage. It is not the same, but has moisture and a sharp, appetizing flavor as well. Add some finely grated carrot, if you like. Add finely chopped parsley, some garlic (especially for chicken and turkey meatballs), ground black pepper and 1/2 teaspoon of salt. Thyme suits beef and lamb, nutmeg adds a festive note to poultry, some cinnamon tastes vaguely Indian. All spices but salt are optional. I cook with very little salt, adjust to your taste. Add whipped whites from two large eggs, or one large egg, if using. Moisten your hands with cold water and mix the meatballs with your hands.
Put a frying pan on a high fire. I use a stainless-steel clad pan, but any surface will do. When the rim of the pan is hot to touch, add some canola oil. Wait until the oil is hot. With wet hands, shape small (2" to 3") round slightly flattened meatballs and place them on the hot pan. You will have ten to sixteen meatballs. If the oil was hot, they shouldn't stick. Cover the pan and reduce the heat to medium. After five to ten minutes, turn the meatballs over, cover, and cook for another five to ten minutes. Serve with any side dish or cook further with sauce. Mustard, mayonnaise, and ketchup are good with meatballs, if not most sophisticated.
Sauce: There are different. For example, add a whole can of canned peeled or diced tomatoes to your pan, water and all. Let it boil down for twenty minutes. Add a tablespoon of sugar and any spices you can think of. Serve meatballs with tomatoes. Trader Joe's simmering sauces, carry, kurma, and others, a good, too. They may be a little too hot for small children, but otherwise delicious. Stock, or just some water with a bay leaf and some chopped carrots and zucchini, and may be an apple, make very tender meatballs.
Meatballs can be reheated or eaten cold. Cold meatballs are good for sandwiches. Cooked meatballs keep in a refrigerator for a week (never had a chance to keep them longer). Meatballs can be mixed and shaped in advance and frozen. They don't take defrosting before cooking.
See also: kitchen, frying pan, gefilte fish, stuffed peppers.