Here's how I learned from watching the Boudreauxs in Texas City clean big gar and cook gar balls. I was small so I may have forgotten something. Nana Boudreaux's cooking was excellent! :-)
1. You take your good sharp filet knife (and you put it out of your way so you don't cut yourself).
2. You rummage in your tool shed and find a good sharp hand axe. Put the gutted gar on a stump or plank and chop it into thick steaks. (If you caught it yourself that day it may still be wiggling, these things are tough!) Skin the steaks, and debone and throw away any gelatinous tissue or cartilage.
3. Some of the rich folks use a meat saw to steak them. I don't have one. A coarse wood saw would probably work.
4. Boil the gar meat (crab meat or another firm white fish can be substituted here for us lazy folks) in crab boil or the other spices you would use for crabs or crawfish. It won't take long to turn pretty and white. Drain the meat well.
5. Mash the gar meat with an equal amount of boiled potatoes. The potatoes can be boiled in the same crab boil, depending on how spicy you want this to be. Add green onion tops, finely chopped. I like a lot of them in mine. Add plenty of bell peppers, some green, some red for added color. Add several cloves of diced garlic per pound of mixture.
6. Mash this mixture until you can form patties or balls with it. Dip the firm patties or balls in an egg and milk mixture then dredge in corn flour (corn meal can be used if you pulse it a few times in a blender) or your favorite fish fry. Deep fry at `350 for ~8-10 minutes or until golden brown.