To save time you can use store-bought pickling spices or you can make your own based on the ingredients above.
Add the allspice berries, mustard seeds, coriander seeds, red pepper flakes, red and black peppercorns, cloves, and cardamom pods to a small frying pan over medium-low heat and toast until fragrant. This will take a minute or two, stir and keep an eye on the spices as they can easily burn.
Remove from heat and place in a small bowl. Use a mortar and pestle to crush them. Add the crushed bay leaves and ground ginger and stir to combine.
Add a gallon of water to a large pot and add 4 tablespoons of the pickling spices (saving the remaining ones for later), add the cinnamon stick, Kosher salt, and brown sugar. Bring to a boil, then remove from heat and let cool to room temperature. Then refrigerate until well chilled.
Once chilled, place the beef brisket in a large, flat container or pan, and cover with the brine. Make sure the brine covers the meat. If the meat floats, weigh it down with a plate.
Refrigerate for 5-7 days and every day flip the brisket over so that all sides get brined equally.
Cook the corned beef:
Remove the brisket from the brine and rinse it with cold water.
Place the brisket in a large pot and cover with at least one inch of water.
Add the remaining pickling spices and bring to a boil, reduce to a very low simmer, and cook for 3-4 hours, until the corned beef is fork-tender.
Once done, place the meat on a cutting board. Cut across the grain to serve.
Add some veggies into the spiced cooking liquid, like cabbage and carrots, and cook them to serve with the corned beef.