First, sage grouse (or any other dark-meated bird) mostly taste like liver if you overcook them. And the more you overcook them, the more they taste like liver.
The first step in cooking sage grouse is to field-dress them IMMEDIATELY. This means within 15 minutes after killing them. Then, ASAP after that, rinse out the cavity with clean water, preferably cold water, and cool the birds down. If the intestinal tract was punctured by shot, it also helps to toss a little salt in the cavity after rinsing it out. All of this minimizes the "sagey" taste that some people object too.
The younger birds are milder flavored, but even the big bombers are much milder flavored if you follow the above. It also helps to age the birds a few days before eating or freezing them, especially the older ones. This makes them tenderer, and can be done in a refrigerator or any other cool place.
The smaller birds can be cooked any way you cook other gamebirds, but (again) don't over cook them. The breast will be tender if you cook it medium-rare (or if you fajitas, as suggested above, cook the meat very briefly, no more than a minute or so. Since one of the things we miss in much wild game is the sweet taste of fat, a little extra fat or even some sweet ingredients help. One thing I like to do with sage grouse (or sharptails, or any other dark-meated bird) is s stir-fry with sweet red peppers, garbanzo beans and maybe even a little sprinkle of brown sugar at the end.
The legs can be tough, especially on the older birds. We often boil them until the meat can be easily pulled off the bones, then make enchiladas.
There are a more details in my wife's book UPLAND GAME BIRD COOKERY, which can be ordered through
www.riflesandrecipes.com. This may sound like a blatant promotion, and is.