Step 1: Combine the ingredients in a large bowl and mix, breaking up any lumps in the brown sugar with your fingers. (Your fingers work better than a whisk or wooden spoon.)
Step 2: Pack in lidded jars and include directions for storing (store away from heat and light) and using. (Figure on 2 to 4 teaspoons per pound of meat.)
How to make this rub your own:
Substitute smoked salt or herb salt for the sea salt.
Substitute light brown, dark brown, turbinado sugar, maple sugar, palm sugar, date sugar, Sucanat (freeze-fried cane juice), etc., for the sugar.
Substitute smoked paprika, hot paprika, or chili powder for the paprika.
Substitute white pepper, lemon pepper, ground green peppercorns, or Sichuan peppercorns (just a little of the latter) for the black pepper.
Kick up the heat with a couple tablespoons of hot pepper flakes.
Add a Southwestern touch with a couple tablespoons ground cumin and / or chili powder.
Substitute mustard seed or ground mustard for the celery seed.