- 2 sweet onions, peeled and quartered
- 2 teaspoons kosher salt
- 1 1/2 teaspoons dark brown sugar, or more to taste
- 1 1/2 teaspoons smoked paprika
- 1 teaspoon ground black pepper
- 1 teaspoon garlic powder, or more to taste
- 1 teaspoon red pepper flakes
- 1 (6 pound) Boston pork butt roast
- 13 fluid ounces ginger beer
- Arrange sweet onions in the bottom of a slow cooker.
- Mix salt, brown sugar, paprika, black pepper, garlic powder, and red pepper flakes together in a bowl until seasonings are well mixed; rub all over pork roast. Place roast in the slow cooker, fat-side up. Brush any leftover seasonings mixture from the work surface into the slow cooker.
- Cook on Low for 1 hour. Pour ginger beer into slow cooker. Continue cooking until roast is tender and pulls apart easily with a fork, 9 to 11 hours.