This is a favorite of mine - My roommate and I came up with this in college:
The gizzards are cleaned and cut into thin slices, then marinated with some soy sauce, chilli flakes, sesame oil, salt, green onion tops (chopped) and ginger julianned.
Marinating for around 15 minutes seems to suffice. We then stir fry it in some oil heated with a few julienne slices of Jalapenos (deseeded). We add some water after the initial frying of the gizzard, and let it simmer anywhere from 30 minutes to a couple of hours (depending on the softness you like). I tend to prefer it a little chewy. Goes great with steamed Broccoli and rice.