In a small, microwave-proof bowl whisk together the dry mustard, brown sugar, salt, turmeric, paprika and garlic powder. In a separate container, combine the pickle juice, water and cider vinegar and have standing by. Place the mustard seed into a spice grinder and grind for a minimum of 1 minute, stopping to pulse occasionally. Once ground, immediately add the mustard to the bowl with the dry ingredients and add the liquid mixture. Whisk to combine. Place the bowl into the microwave and heat on high for 1 minute. Remove from the microwave and puree with a stick blender for 1 minute. Pour into a glass jar or container and allow to cool uncovered. Once cool, cover and store in the refrigerator for up to 1 month.