Line the bottom of the slow cooker with thickly sliced carrots.
Heat a large, heavy-bottomed skillet over very high heat and swirl in 4 Tbsp cooking oil (I used extra light olive oil since it has a high smoke point). Once the skillet is blazing hot, sear and brown all of the sides of your beef roast (2-3 min per side). Watch out for splatters and wear an apron! Transfer the roast to a slow cooker.
Saute your thickly sliced mushrooms and finely diced onions in the same skillet over medium/high heat until soft (5-7 min) then stir in the pressed garlic and saute another minute then remove from heat.
In a medium sauce pan, whisk together 2 cups broth, 1 cup heavy cream, 1 packet onion soup mix, ½ Tbsp Mrs. Dash, 1 tsp salt, and ⅓ cup all-purpose flour. Once it's whisked together, heat on med/high whisking until you have a gravy consistency.
Stir mushroom/onion mixture into the gravy, whisk in the wine and bring to a simmer.
Pour mushroom gravy over the meat in the crockpot, cover with lid and cook on high heat for 6 hours.
Just before serving, transfer the beef to a serving dish and pull it apart with forks. Pour the gravy over the beef right after it's shredded, while it's hot, so it can absorb some of that gravy. Add more salt to taste.
