Peel and cut the medium onions (whatever type you prefer, white or yellow etc) into 8ths, and place them in the bottom of your crock pot.
Open up the packaged corned beef and pour all of the juices contained in the bag into the crock pot (the producer's directions recommend using the juices, as well).
Place the corned beef on top of the onions, then sprinkle with the spice packet.
Pour the beef broth over the corned beef, careful not to dislodge too much of the spice packet ingredients, then do the same with the can of stout.
Arrange the sliced red onion over the top of the beef.
Put the crock pot on low and cook for 4 hours, then turn the beef over and cook an additional 4 hours (or you can cook on high for 2, turn, and cook an additional 2 or until it is as tender as you'd like).
Slice and serve with Simmered Cabbage recipe #100417, carrots, and potatoes of your choice.
Note: although you can use Guiness in this instead of the Young's, I recommend trying to find the double chocolate stout because of the delicious, rich, non-bitter taste it imparts to the corned beef! If you'd still like to experience the richness of a bit of chocolate, take 1 1/2 teaspoons of unsweetened cocoa powder and mix it with a bit the beef broth until it's well mixed and smooth, then whisk it into the rest of the broth and proceed as the recipe describes. Wonderful!