Add chopped onion, garlic cloves, mustard seed, whole peppercorns, whole cloves, allspice berries, crushed red pepper flakes, coriander seeds, and bay leaves in the bottom of the pot.
Place corned beef on top and pour in beef stock.
Close the lid and make sure it’s latched completely. Turn the valve to seal and set Instant Pot to cook on “stew/meat” setting for 75 minutes.
Once time is up, let it do a natural release for 15-20 minutes and do a quick release. Take the brisket out but don’t discard the cooking liquid.
Cooking Potatoes:
Place potatoes into a separate pot and pour in the liquid from cooking corned beef until all potatoes are covered.
Cook potatoes on stove-top until they start to be tender but not too soft. (Don’t overcook or potatoes will be hard to cut.)
Take potatoes out of the liquid and let them cool enough to be handled.
NOTE: You can save corned beef and potatoes in a food storage container, in the refrigerator, or prepare the hash right away.
Cooking Corned Beef Hash:
Dice onions, potatoes, and corned beef and set aside.
Preheat a large pan over medium heat and add 2 tbsp of butter to melt. Saute diced onion in butter until it browns.
Add diced corned beef and cook it together until corned beef is heated through.
Add diced potatoes and remaining 2 tbsp of butter. Season with salt and pepper and once butter is melted, stir everything together. Let is saute for a few minutes before mixing again.
Cook for about 15 minutes but don’t mix too often, so it gets crispy on the bottom before you stir.
Stir in some chives and parsley and serve.
To Add Eggs:
Lower the heat to medium-low.
Make four little wells in the cooked hash and crack and egg into each well.
Season each egg with a some salt and pepper, cover the pan with a lid, and cook until the eggs are cooked as desired.
Notes
NOTE: Nutritional value is calculated with eggs.
Make Ahead: If you're making it from scratch, you can definitely cook the corned beef and then the potatoes and store them separately in the refrigerator. Make sure to store them in airtight containers. Boiled potatoes and corned beef are actually easier to cut when they're cold. If you'll be using leftover corned beef, you can also cook the potatoes ahead of time. That's really the only way to make it ahead of time. If you already have the cooked corned beef and boiled potatoes, the recipe is a breeze.
Reheating: The best way to reheat it is in the pan. Preheat the pan on medium heat and reheat the hash for a few minutes until it’s hot throughout. If you need to, add a tablespoon of butter or oil while reheating.