Sprinkle all sides of the beef with 3-4 tablespoons of the rub. Don't be shy with it.
Wrap the beef tightly in foil and refrigerate for up to 3 days, turning every 12 hours. The longer, the more flavor.
Fire up your Big Easy.
Remove the roast from foil and place into the Big Easy basket. Lower into the cooker and cook until the center reaches 125 F for rare, about 45 minutes. It's easy to over-cook the beef, so start checking the temperature after 30 minutes.
Remove from the cooker and let rest 10 minutes before slicing thin.
For the sandwiches
Toast buns, if desired
Slather buns with the sauce.
Add plenty of onion then mound up the thinly-sliced beef.