Trim excess fat from the brisket, leaving a thin layer
Season the brisket generously with salt, pepper, garlic powder, and onion powder
Optional: sear the brisket in a hot skillet for 2 to 3 minutes per side
Place sliced onions, garlic, or other aromatics in the bottom of the slow cooker
Add the brisket on top of the aromatics
Pour in beef broth, water, barbecue sauce, or a mix of liquid ingredients
Add enough liquid to cover the bottom of the slow cooker, not the entire brisket
Cover and cook on low for 8 to 10 hours
Or cook on high for 4 to 6 hours
Check for tenderness with a fork
Cook until the brisket is very tender and easily shreds
Remove the brisket and let it rest for 10 to 15 minutes
Slice against the grain or shred as desired
Spoon cooking juices over the brisket before serving
Optional: thicken the cooking liquid into a sauce or gravy
Optional: refrigerate overnight and slice after chilling for cleaner cuts