Pat meat dry with paper towel and season all sides liberally with salt and pepper. 

Heat a large pan or dutch oven over medium high heat for 5 minutes. Add oil to the pan, allowing it to heat for 1-2 minutes before carefully adding the meat to the pan. Sear each side and edge of the meat until golden brown, about 3-5 minutes per side. 

Turn a 6-quart slow cooker on low and add butter. Once butter has melted, and half of the ranch seasoning and half of the au jus seasoning to crockpot once butter has melted and let the seasonings bloom for 2-3 minutes.

Add the roast to the slow cooker and sprinkle with the remaining seasonings.

Add half of the pepperoncinis and about ¼ cup of the pepper brine over the meat. Cover and cook on low for 8 hours.

After 8 hours, transfer the meat to a large bowl and shred. 

Meanwhile, strain the liquid from the crock into a medium sized sauce pot, returning any solids to the slow cooker along with the shredded meat. Slice the remaining pepperoncinis and add to the meat. 

Add the beef stock to the sauce pot. Add as much of the remaining pepper brine as you’d like, to taste.  Simmer over medium-high heat until the liquid has reduced and thickened into a thin gravy.

Serve Mississippi pot roast over mashed potatoes or buttered egg noodles with gravy.