This recipe is from Mike Mills cookbook Peace Love and Barbecue. Another fine book with lots of recipes and a bunch of good stories.
Don't think it's the exact recipe that in the restaurant, since I did find Magic Dust for sale on the Internet and it's listed as having 18 ingredients. The cookbook recipe only has nine ingredients.
This is a big recipe, makes about 2 1/2 cups. You may want to cut it in half.
To make it a little more hot and spicy, increase the mustard powder and black pepper to 1/4 cup each.
1/2 cup paprika
1/4 cup cosher salt, finely ground (I use fine sea salt)
1/4 cup sugar
2 tablespoons mustard powder
1/4 cup chili powder
1/4 cup ground cumin
2 tablespoons ground black pepper
1/4 cup granulated garlic
2 tablespoons cayenne pepper
Mix all ingredients and store in a tightly covered container.