1. Place corned beef in a pot or a large bowl, cover with cold water and let stand for 1 hour (to make it less salty).
2. Preheat oven to 350F (180C).
3. Drain the brisket and place fat side up in a baking dish, previously covered with a large piece of heavy aluminum foil.
4. Sprinkle corned beef with coriander, mustard seeds and crushed bay leaf and pat into the brisket. Generously sprinkle with freshly ground black pepper.
5. Wrap the meat with foil and bake in the preheated oven for about 2 1/2 hours. Continue baking until the brisket is fork tender. Open the foil wrapping and bake for additional 10 minutes.
6. Scrub the potatoes under running water and trim away any blemishes. Pat them dry, sprinkle with olive oil, toss, cover with foil and bake for 1 1/2 hour (check for doneness by piercing with a fork).
7. Meanwhile, cut cabbage in half. Then each half in 4 wedges.
8. Heat olive oil in a large skillet over medium-high heat. Add cabbage wedges and sear on both sides until nice brown color is achieved, about 2 minutes per side.
9. Transfer cabbage to a baking sheet, previously covered with parchment paper (or brushed with a little olive oil). Sprinkle with garlic powder, salt and pepper. Bake in the oven for about 20-25 minutes.
10. Cut potatoes in half, top with thin slices of butter, sprinkle with salt and rosemary.
11. When the corned beef is ready, allow it to rest and slice against the grain. Serve with potatoes and cabbage.