I would roast the turkey legs-they will be moist and have more flavour than if they were steamed. The sinew etc won't get tough as long as the meat is not over cooked.
A few hours in a slow cooker will result in meat that falls off the bone.
You shouldn't need to cook the kidney beans-I'm assuming they are tinned. You can lightly sauté the onions-then let cool before combining with the raw mince. and some chopped fresh or dried herbs and maybe some breadcrumbs. An added egg is ok-it will help bind the meat and keep it all moist.
You can use turkey mince for any other kind of mince including beef,lamb or pork...burgers,meatloaf,cottage pie,mince and onions.



