Step 1

Put the corned beef on the bottom of the slow cooker, and fit the new potatoes in around it, then pour the beer over the corned beef. Sprinkle with the seasoning packet. Add the onions and carrots, then sprinkle with 1/4 tsp of kosher salt. Add the cabbage on top, and sprinkle with another 1/4 tsp of salt and the ground mustard. (Make sure the lid can close on the slow cooker. Move the cabbage around or remove some to make sure the lid seals against the crock.)

Step 2

Cover the slow cooker, and cook on low for 8-10 hours, or high for 4-5 hours.

Step 3

Remove the vegetables to a serving platter with a slotted spoon, and moisten with the juices in the slow cooker. Slice the corned beef crosswise into 1/2" thick slices, put on the platter with the vegetables, and moisten with more of the juices from the slow cooker. Serve.