Gather all ingredients and measure them out.

In a dry skillet over medium heat, toast the mustard seeds, coriander seeds, black peppercorns, and allspice berries until fragrant.

Remove from heat and let the spices cool completely.

Grind the cooled spices using a spice grinder or mortar and pestle until finely powdered.

In a mixing bowl, combine the ground spices with the remaining ingredients: crushed red pepper flakes, garlic powder, onion powder, ground ginger, and ground cinnamon.

Stir well to blend everything evenly.

Transfer the spice mixture to an air-tight container.

Label and date the container for storage.

Use your homemade corned beef spice to season corned beef or add it to soups and stews.