Add the ground mustard seeds to a medium-sized glass dish that has a lid.

Add the mustard powder, apple cider vinegar, warm water, sea salt, raw honey, turmeric and garlic and stir everything until combined well. If you'd like to add any additional herbs or spices, now is the time.

Place the lid on the glass dish and transfer to the refrigerator. Wait at least 12 hours before using. Store leftover mustard in the fridge. This should last several months.