And if you insist on going after a big bull trophy Mormon, about all you can do with them is make sausage. It's better if you do a three part mix with pork and venison, and be sure and use plenty of sage.
A good, long soak in brine will eliminate most of the gamy flavor. Now, for the toughness, you'll want a long, slow simmer. Make sure your water or stock never reaches a boil. They can't stand too much heat.
The young ones are if they're plump and tender, but full grown adult Mormons, especially the older males, tend to be kind of tough and stringy and often have a rank, gamy flavor.