Trim as much fat as possible, from the outside of the cheeks and remove any silver skin. Cover all sides with ProQ Beefy Rub (you could substitute this with a 40/60 mix of salt and pepper). Finish off with a light sprinkling of smoky Paprika and allow to rest at room temperature for 1 hour.
Peel, halve and finely slice the red onion. Place in a small dish, add the White Wine Vinegar, a squeeze of Lime juice and Sea Salt and give it a stir. Set aside in the fridge.
Set up your BBQ Smoker for low and slow, we recommend using the minion method with the water pan in an 2/3 full of water. Once your BBQ has reached temperature place the Beef Cheeks on the grill, put the lid on and pop a chunk of Hickory wood through the lower door, onto the charcoal.
Once the internal temperature of the cheeks reaches around 160°F (70°C) - 170°F (75°C) They will seem to sit there and not increase temp for quite some time... This is known as "The Stall". It's nothing to worry about and is completely normal and at this stage we recommend that you place the beef cheeks in a shallow dish, pour in the beef stock and cover with foil, before placing them back on the smoker.
When the internal temperature of the cheeks reaches 195°F (90°C) - 205°F (95°C) check doneness by probing the meat with a toothpick, once it slides in and out with almost no resistance the cheeks are done and can be put aside to rest for an hour.
Use 2 forks to shred the Beef Cheeks, assemble your tacos and enjoy!