Rinse the gizzards under cold water, reaching into their crevices with your fingertips to get out any grit that might have remained behind when they were cleaned and packaged. Part of the gizzard is covered by a sheath of silverskin, a tough grey connective tissue. Slip the tip of a thin, sharp knife under the silverskin and peel it away from the underlying muscle.

Arrange the gizzards in a slow cooker or casserole dish, along with onions, garlic and any other aromatic ingredients you wish. Season them with salt and pepper; then add enough chicken broth, water or wine to cover them.

Cook the gizzards at your slow cooker's "Low" setting for 4 to 5 hours, until they're tender and not chewy when you taste a sample slice. In the oven, cook at 275 to 300 degrees Fahrenheit for the same length of time. Turkey gizzards are larger than chicken gizzards and will take longer to cook.

Remove the gizzards from the braising liquid and transfer them to a bowl. Serve them hot with a sauce made from the cooking liquid, or cool them and use the cooked gizzards as an ingredient in other recipes.

Clean your gizzards under cold running water, removing any residual grit from inside. Dry them carefully; toss them with coarse salt and any other seasonings you wish. Cover the gizzards and refrigerate them overnight.

Rinse the seasonings from the gizzards and pat them dry. Place them in the crock of a small slow cooker or in a heatproof casserole dish. Pour in enough rendered duck fat, chicken fat or lard to completely cover the gizzards. Gently cook the gizzards for 5 to 6 hours on your slow-cooker's "Low" setting or in a preheated oven at 225 degrees Fahrenheit for 2 to 3 hours.

Cool the gizzards in their protective layer of fat; then refrigerate them. If you don't wish to store them in the casserole dish, transfer them first to a clean heatproof storage container with a lid.

Remove gizzards from the fat as needed, heating them gently to melt the fat and then wiping it away with a paper towel.