Toast coriander seeds, mustard seeds, peppercorns, and anise seeds in a hot cast-iron skillet over medium heat for 2 - 3 minutes, or until fragrant.
Add bay leaves and red pepper flakes during the last 30 seconds. You basically want to wake up their flavors.
Pour the corned beef seasoning into a spice mill, coffee grinder, or a Ninja blender. Pulse a few times, just enough to crush the spices and release their flavor.
Store the corned beef seasoning in an airtight container until needed. Use as much of the corned beef spices as you'd like to season your corned beef before cooking it.
