Place a large 12-inch skillet (preferably, cast iron
) over medium heat. When water flicked onto the skillet sizzles, add the beef. Season with salt and pepper. Cook for 5 minutes, or until the meat begins to brown, breaking it apart with the back of your spoon to form bite-sized chunks. Add the garlic and oregano and sauté for 3 minutes more, until very fragrant. Remove the meat mixture to a bowl and set aside.