In a large baking dish, whisk together the coffee beans, chile powder, brown sugar, smoked paprika, kosher salt, cumin, and black pepper. Press the beef into the spices and pat the spice mixture all over.
Place the onion in the bottom of a slow cooker. Place the spice-covered beef over top. Top with the garlic, chipotles in adobo, maple syrup, beer, and balsamic vinegar.
Cover and cook until easily shredded, on low for 6-8 hours, or on high for 4 hours.
Remove the beef from the slow cooker and shred using two forks. Make a slurry by whisking together 2 tablespoons of cornstarch with 2 tablespoons of cold water. Whisk the slurry into the slow cooker liquids and set the slow cooker to high. Add the beef back to the slow cooker, cover and cook for an additional 30 minutes.
Serve warm in tacos, on sandwiches, over mashed potatoes, or as desired.