Heat a large non-stick skillet to medium-high (add 1 tablespoon olive oil if using a stainless pan). Liberally season chuck roast with salt & pepper. Add to skillet and sear on all sides until it naturally releases for pan. Transfer to slow cooker.
Add beer, minced garlic and lime juice to slow cooker. Cover and cook on low for 8 – 1- hours.
Remove chuck roast from slow cooker and reserve 1 cup cooking liquid. Shred beef and season with taco seasoning. Return beef and cooking liquid to slow cooker and stir until seasoning is evenly distributed. Cook on high for about 30 minutes.