This is so easy even I can whip it together. This has been a family favorite for years, although I only recently tried it with venison (original recipe calls for beef). This comes from the Circle of Friends cookbook, an unpublished compilation of recipes my wife's aunt and her friends authored.
2 lbs venison cut into 1-inch pieces*
1 envelope onion soup mix
1 can cream of mushroom soup
1-1/2 cups sliced mushrooms
3/4 cup of red wine
Combine all ingredients in crock pot, stir well, cover and cook 8--12 hours on low (or 5 to 6 hours on high). Supposedly you can't peek at it during this time or you'll not only wreck it, you'll strike out on your next three deer tags.
Serve any way you like but it's great over brown rice or noodles. I definitely like some fresh-ground black pepper over mine.
* I used 2 pounds of back strap from a younger deer and it ended up more tender than beef.