Step 1

In a 5-to-6-quart slow cooker, place the carrots, onion and potatoes. Place corned beef, fat side up, on top of the vegetables and sprinkle with pickling spice. Pour the beers over the vegetables and brisket. Sprinkle with the sprigs of fresh thyme. Cover and cook on high until corned beef is tender, 5-6 hours or 10-12 hours on low.

Step 2

Arrange cabbage over corned beef, cover, and continue cooking until cabbage is tender, 45 min to 1 hour (or 1 1/2 to 2 hours on low). Thinly slice the corned beef against the grain and serve with the vegetables and cooking liquid with the horseradish sauce.

Step 3

Cut the corned beef into 2-3 chunks so it cooks faster and more evenly. Add to the insert of a 6 quart Instant Pot with the fat cap up. Layer with the onion, spices, thyme and beer. Cook on HIGH pressure for 90 minutes then do a quick release.

Step 4

Add the potatoes, carrots and cabbage to the insert, close, and set to HIGH pressure for another 5 minutes. Natural release for 5 minutes, cut, and serve.

Step 5

Mix the sour cream and horseradish together in a small bowl. Refrigerate for up to 1 week.