Cook Corned Beef: Remove corned beef from packaging. Soak in water for 1.5 to 2 hours to reduce saltiness from brining solution.
Mix celery seeds, mustard seeds, whole peppercorns, and coriander seeds together in a small bowl.
Place soaked corned beef in a large pot. Add spice blend and quartered onion to pot. Cover with cold water.
Bring water to a boil over medium-high heat. Once boiling, reduce heat to a simmer.
Allow corned beef to simmer for 45 minutes to an hour per pound, ensuring it remains covered with water throughout the cooking process. Occasionally skim any foam or impurities that rise to the surface.
Check doneness of the corned beef by inserting a fork into the thickest part. It should be fork-tender.
Once cooked to perfection, remove from the pot and let it rest for a few minutes.
Prepare Hash and Eggs: Dice cooked corned beef into small, bite-sized pieces.
Boil diced potatoes in salted water until just tender. Drain and set aside.
Heat vegetable oil over medium heat in a large cast iron skillet. Add chopped bell peppers, onions, and garlic, and sauté until softened and translucent.
Add boiled diced potatoes and diced corned beef to skillet. Cook, stirring occasionally, until the potatoes start to crisp and turn golden brown.
Sprinkle dried thyme, dried rosemary, paprika, salt, and pepper over the mixture. Continue cooking until the hash to develop a delicious crust, about 7 to 10 minutes.
Taste the hash and adjust seasoning as needed. Add more salt and pepper if necessary.
Prepare poached or fried eggs to serve on top of the hash for an extra layer of flavor and texture.
Spoon the corned beef hash onto plates and top with poached or fried eggs.
Notes
Canned corned beef: Making corned beef hash and eggs using canned corned beef is a convenient and quick way to enjoy this classic dish. Use 1 can (about 12-16 ounces) of canned corned beef. Break it up with a fork and add it to the skillet, mixing it with the potatoes and vegetables.