Brown the ground beef. This can be done in the Instant Pot on the saute setting or in a separate pan, whatever you prefer.
Add the broth (If you used the Instant Pot to brown the meat, make sure to deglaze the pot!) ground beef, au jus seasoning, onion, diced potatoes and the frozen peas and carrots to the liner of the Instant Pot.
Cook on Manual HIGH for 0 (yes, ZERO) minutes.
While the stew is pressure cooking in the Instant Pot, make a paste with the butter and flour.
Quick Release the pressure when the Instant Pot is done.
Turn the Instant Pot onto saute. When the stew begins to boil, add the butter and flour paste to the Instant Pot.
Stir while the paste is melting and thickening the stew. If after all of the paste has melted, you still want the stew thicker, simply make a little bit more paste and thicken to your liking. The measurements above are exactly the way I eat it.
Serve with a crusty dinner roll and enjoy!