Mix the ingredients together with a blender or immersion blender. I use an immersion blender and feel like it does a great job and I have less clean-up than if I used a regular blender. Taste and adjust the ingredients or spices if needed.
For a thicker ranch dip, use 1 cup of sour cream and add a little more spice mix if needed.
This should keep in the fridge as long as any of the ingredients would keep on their own. Use your best discretion.