In a large bowl, marinate corned beef with sugar free maple syrup, mustard, garlic powder, salt, pepper, and marjoram for 15 minutes or up to 2 hours.
Add the beef broth to the Instant Pot pressure cooker.
Using an insert or basket for the Instant Pot, add in the corned beef and set to high pressure for 90 minutes. Once the timer is up press cancel and allow it to do a natural release. This may take about 10 minutes.
Once the Instant Pot has depressurized, remove to corned beef, and cover it to allow it to rest.
Drain the instant pot and put a basket in with the carrots (or cauliflower florets), cabbage, and 1/2 cup of water. Cook for 4-5 minutes on high pressure.
Serve corned beef with cabbage and carrots or cauliflower.
What is Corned Beef? Corned Beef is a beef brisket cured in brine and boiled, served hot typically with cabbage, or cold, sliced for sandwiches. It's not the same thing as pastrami. Both corned beef and salami are cured meats, which means they've been brined in a salt water solution. The brine may or may not include spices and seasoning. The cooking process differs after the curing process. Corned beef is boiled while pastrami is smoked. Corned beef is definitely gluten-free!