4ozfresh button mushrooms, You could also get cremini mushrooms and slice them into quarters, since they're larger. Button mushrooms can be left whole.
2carrots, cut into 2-inch pieces
1rib of celery, cut into 1-inch pieces
A few fresh thyme sprigs
A few fresh rosemary sprigs
1/4cupdry red wine
1TBSPstone ground mustard, Dijon mustard will also work.
1tspbeef bouillon paste, Better Than Bouillon works really well.
1TBSPall purpose flour
Fresh chopped parsley, to serve
Place the garlic, onions, potatoes, mushrooms, carrots, and celery into the slow cooker. Create a bit of a dip in the middle to nestle the roast.
Heat the oil in a large skillet or pan over high heat. Rub the roast with a generous amount of salt, pepper, and chopped fresh rosemary or thyme. Transfer the roast to the hot pan of oil and cook, for about 5-6 minutes each side, until browned. This will give the exterior a nice crust, but don't cook it anymore than that. When done, transfer the roast to the slow cooker; leave the skillet on the stove.
To the skillet where you browned the beef, add the beef broth, red wine, mustard, brown sugar, balsamic vinegar, and bouillon paste over medium-high heat. Bring to a simmer, whisking the ingredients together until well-mixed and the sugar and bouillon have dissolved. Scrape up any pan bits while you're at it—this will add to the flavor of your gravy!
Remove the skillet from the heat, whisk in the flour, and carefully pour the liquid into the slow cooker over the beef and vegetables. This juice will thicken as it slow cooks, also taking in the natural juices from the beef.
Nestle a few fresh thyme and rosemary sprigs around the beef and vegetables. Cover and cook on low for 8 hours (or on high for 5-6 hours), until the meat is tender and falling apart and the vegetables are soft. For tender beef that can be shredded, you're looking for an internal temperature of 190-195º. Taste test and season it a little extra if necessary.
Transfer the meat to a cutting board. Shred it or slice, then place it into a serving dish with the vegetables. Drizzle with gravy and garnish with fresh parsley.