There is a local place that cooks amazing fried chicken gizzards.  Somehow they are really tender, and yet the breading on them is still crispy.  Every time I try to make them they turn out extremely chewy.  What could their secret possibly be?  I have tried getting really fresh (never frozen) gizzards from local farms, but I still can't cook them right! 
In order to get them tender as most restaurants, you would need a pressure cooker that will get them even more tender than boiling; also, braising then simmering works well.  After you either pressure cook, boil, or braise, I recommend cooling them in buttermilk for at least 2 hours; adding a little vinegar to the whole milk works. The milk and the vinegar will help break down some of the tough tissues, and pull out some of the gamy taste that things like gizzard, heart and other organs have.  Next, make your breaded seasoning, and toss them in breading and fry; 350° F is optimal frying temperature for almost everything. 