1. Combine the seasonings for the dry rub and set aside.
2. Cut up all veggies and set aside.
3. Sprinkle some flour all over the roast.  Next sprinkle about 1/3 of the dry rub on top. Rub it in and repeat on the other side.
4. Heat up a large cast iron skillet over high heat until the pan is smoking.  Add a little oil and carefully place the roast in the skillet and allow it to sear for approx. 5 minutes on each side. If the roast is very thick, do the sides as well.  Transfer the roast to a slow cooker.
5. Place the veggies in a bowl and drizzle 1 Tablespoon oil on them and add the remaining dry rub.
6. Add the veggies to the skillet the roast was seared in and cook them on low/medium for approximately 4 minutes, adding oil if necessary.
7. Add the garlic and mushrooms, give a good stir.
8. Carefully add the beer and scrape up any bits that are on the bottom of the pan.
9. Transfer the veggies to the slow cooker.
10. Add the beef broth, cover with the lid and cook on low for 6-7 hours or until meat falls apart.

For the Gravy (optional but SO worth it!)

1. Take the roast out of the slow cooker and place on a large platter
2. Pour the liquid out INTO A STRAINER into a large saucepan
3. Put the veggies back into the slow cooker, along with the meat
4. Combine 3-4 Tablespoons flour with the same amount of milk or hot liquid from the slow cooker. Combine until there are no lumps and add to the liquid in the saucepan over HIGH heat until the gravy thickens. You can always add more flour/milk so start slowly adding as you go until you get the desired thickness. Strain again in a VERY FINE strainer and return to the slow cooker.
5. This is an extra step but you will NOT regret it!