What cut of beef works best in a slow cooker?
Chuck roast is the MVP here. It has enough fat and connective tissue to break down into that fall-apart texture. Bottom round can work, but it is leaner and can shred a bit drier.
Should I cook the roast whole or cut it into chunks?
Cook it whole for the best, juiciest shred and less fuss. If your roast is too large to fit, cut it into 2 to 3 big pieces (not small cubes) so it still braises instead of boiling.
Do I have to sear the beef first?
No. The slow cooker will still get you tender beef. But if you have 8 to 10 extra minutes, searing adds a deeper, roastier flavor. If you skip it, I recommend not skipping the Worcestershire and tomato paste.
Can I cook this on high instead of low?
Yes. Cook on HIGH for 4 to 5 hours or LOW for 8 to 9 hours, until the beef is fork-tender and shreds easily. Slow cooker models vary, so let tenderness be your final timer.
How do I thicken the gravy?
A cornstarch slurry is the cleanest fix. Mix 2 tablespoons cornstarch with 2 tablespoons cold water, stir it into the hot liquid, and cook on HIGH for 10 to 15 minutes until thickened. If you want it thicker, add another slurry using 1 tablespoon cornstarch + 1 tablespoon cold water.
What about all the fat on top?
Chuck roast can render a lot. If the surface looks greasy, skim it with a spoon before thickening the gravy. For an even cleaner skim, chill the cooking liquid briefly so the fat firms up, then lift it off.
Can I add vegetables?
Absolutely. Add carrots and mushrooms at the start. Add peas at the end so they stay bright. If you add potatoes, cut them large so they do not disappear into the gravy.