Liberally season all sides of your chuck roast and short ribs with salt (kosher ideal but any salt works) and pepper.
Start with saute mode on, add the dried chilies directly to the pot and toast them for a few minutes on both sides, stirring frequently to prevent burning. Remove and set aside, leaving the seeds in the pot.
While still on saute mode add oil, then the short ribs. Cook undisturbed for 3-4 minutes to sear. Rotate and repeat until all sides are seared brown. Remove and set aside, then repeat with the chuck roast, adding additional dash of oil to the pot if necessary. Remove the roast and set aside.
Still on saute mode, add the garlic and onions. Saute until fragrant, about 2 minutes. To the onions and garlic, add seasonings, tomato paste, and chipotles in adobo and cook until onions start to soften, about 3-4 minutes.
Add the beef stock and apple cider vinegar, and loosen up any brown bits from the meat and onions on the bottom of the pan, they will impart lots of flavor to this base. Add the short ribs and chuck roast back into the pot. Add a little more stock if needed so liquid comes half way up the roast.
Pressure cook for 75 minutes (add 15 minutes more for each additional half pound of meat), then use the steam release. Beef is ready when it shreds with no resistence. Once it’s finished cooking, use tongs to carefully remove the meat and place into a large heat-safe bowl. Let rest for 5 minutes then shred.
Strain the solids out of the sauce by placing a fine mesh strainer over a large bowl. Toss the solids and reserve sauce for dipping. Remove the excess fat from the sauce by tapping the surface of the sauce with a folded paper towels until it absorbs most the fat. This may take a few passes with new paper towels.
Taste your sauce and add the salt, about 2-4 pinches is usually needed.