Mix together the breadcrumbs and water and set aside.
Then combine the beef, egg, cheese, onion, garlic, salt, oregano and pepper to taste. Using your hands, mix the ingredients together. Blend the bread crumb mixture into the meat mixture.
Shape into 2-inch balls.
Heat oil in a large oven-safe pan. When oil is very hot but not smoking, fry meatballs in batches. When the bottom half of the meatball is brown and slightly crisp, turn and cook the top half.
Pour the marinara sauce into the pan with the meatballs and cover with foil. Bake in the oven for about 15 minutes, or until the meatballs are cooked through.
Remove the foil and add the cheese. Bake until the cheese is melted and golden, about 10 more minutes.