Rubbery turkey gizzards have long been chopped up and used for giblet gravy. These larger versions of chicken gizzards need not be consigned to a subordinate role, though: They make fine cold weather comfort food. Cooked until tender in a slow cooker, they go well with rice or noodles. Serve them with or without the rich gravy. Butchers who sell poultry may sell turkey gizzards by the pound, as they do chicken gizzards.
Rinse gizzards well in cold water and cut the largest ones so pieces are all approximately the same size. Cut the onion into sliver-thin slices.
Start the slow cooker. Heat 20 oz. or more of chicken broth in a saucepan until steam starts to rise, and then pour it into the stoneware. Add the onion and gizzards.
Add more broth if necessary to cover the gizzards. Turn the slow cooker to its low setting – between 250 and 300 degrees.
Check the slow cooker after two hours and add salt and pepper to taste. Add 1 tsp. of rosemary and more chicken broth if liquid has boiled away. Adjust the temperature so the liquid steams but does not boil.
Cook the gizzards for two more hours. Check the gizzards for tenderness and seasoning. Cook up to six hours, if necessary.
When gizzards are completely tender, remove them with a slotted spoon and cut them into bite-size pieces or slice them for casseroles.
Make a roux with 1/4 cup of butter or margarine and 1/2 cup of flour. Melt the butter over low heat and whisk in the flour, cooking until the roux turns a golden brown.
Add the roux slowly to the broth in the slow cooker, whisking to incorporate, until you have a rich gravy. Season with salt and pepper to taste.
Return the gizzards to the gravy to reheat. Serve on noodles or with rice.