I love gizard stew. Here is a very simple way of doing it. You'd need say about 3-4 pounds of cizzards. One large onion. Some oil for frying, salt and pepper to taste. Half of a tea spoon baking soda. Boiling water. Use Dutch oven or simular.
Chop onion, I like to dice. Preheat some oil in the dutch oven add onions and a pinch of salt. Sautee until golden brown. That might take a litle bit of time, make sure not to burn them, but they do have to be golden brown. At that time add gizzards. Sautee on all the sides, they should be visibly fryed, kind of brownish color. At that time add soda and maybe a half a cup or a cup of boiling water, mix well. Keep stiring till water evaporates. Add salt and pepper mix well. Then add more water, enough to cover all the gizards, bring it to boil, should not take long as you are adding already boiling water, lower the heat and cook the way you would cook soup, you know kind of light boiling. Cook for good 3-4 hours. The liquid should reduce by half. Taste reseason. Ready to serve. Add this point it is up to you what to serve it with. I don't know why, but I love noodles with gizzards. Serve the noodles on the plate, put some gizzards on the top, poor some of the liquid fro the pot over it, yum.
If you are up for it, after water boils, put the whole pot into the oven, at about 350 deg. Cook it covered, but for the last half an hour take the lid of, it will get this beautiful dark brown color.