Blend all ingredients until fine in a food processor or blender (I use my nutri-bullet). It should take just seconds. Store in an airtight container.
When you are ready for ranch dressing, whisk (you must use a whisk!) 1 tbsp of dry mix, 1/3 cup mayo, 1/3 cup milk, and 2 tsp lemon juice. Add more dry mix to taste. Enjoy!