Set the Instant Pot to Saute mode. Heat 2 tbsp olive oil until it begins shimmering (this takes about 2 minutes). Pat the chuck roast dry and season it on all sides with salt, pepper, garlic powder, and onion powder. Brown the roast on all sides for about 3 minutes per side, then remove it and set it aside.
Quarter the potatoes and the onions and cut the carrots into 4 inch pieces. Add the onion and carrots to the IP and saute them together for about 5 minutes, stirring occasionally. Remove them and set them aside.
Deglaze the pan with ½ cup beef stock, scraping the bottom with a wooden spoon. Add the rest of the stock, vinegar and garlic, then put the roast back in.
Cover and set to Meat/Stew for 80 minutes. Allow the pressure to Naturally Release. Remove the lid. Remove the roast, set it on a plate, and spoon about 1/4 cup of liquid from the Instant Pot on top. Cover to allow it to rest while the vegetables cook.
Add the onions, garlic, carrots, potatoes, and rosemary and thyme to the Instant Pot and cover. Set to Meat/Stew (or High Pressure) for 5 minutes, then Quick Pressure Release (turn the vent knob to release the steam quickly). Remove the vegetables with a slotted spoon and set them aside, so only the drippings and broth are left. Make the gravy (see below).
When you’re ready to serve, use two forks to pull the pot roast apart into bite-sized pieces. Discard the fat cap and any tough fatty pieces. Serve the vegetables and pot roast with a good drizzle of gravy and parsley.
To Make the Gravy
Set to Sauté mode. In a small bowl, whisk together a slurry using 2 tsp. arrowroot powder and a tablespoon or two of broth from the Instant Pot.
Whisk in another 2-3 tablespoons of broth from the Instant Pot.
Whisk the mixture into the broth in the Instant Pot, then stir in the coconut aminos. Continue to stir often until thickened slightly, about 3-4 minutes. Season to taste with salt and pepper.
Notes
To Make Pot Roast in the Slow Cooker / Crock Pot: Follow the directions above, but:
Season and brown the meat in a large stock pot, then transfer the meat to your slow cooker.
Add the liquid to the slow cooker. Cook on high for 5-6 hours or low for 8-10.
Add the vegetables (carrots, onions, potatoes) to the mixture during the last 60-90 minutes so they cook but won't get too mushy.
To make gravy, use the liquid from the slow cooker in a skillet over medium heat. Stir in the slurry and simmer together until slightly thickened.