Brown Ground Beef: Before cooking this dish, you’ll need to brown the ground beef in 1 tablespoon cooking oil. I prefer to do this in a separate skillet over medium-high heat which takes 5 to 7 minutes. (I think a separate skillet gives the meat the best texture.) If you don’t want to use the skillet, you can absolutely brown the meat right in the Instant Pot, using the Saute function on Normal / Medium.
In the bowl of the Instant Pot combine browned ground beef, bell pepper, onion, ketchup (or BBQ sauce), Worcestershire sauce, brown sugar, Dijon mustard, salt, and black pepper. (Note: If you don't want to add the pot-in-pot potatoes, skip ahead to Step #5.)
Top the meat with a 2” metal trivet. Place a 7” wide glass bowl on top of the trivet. (Be sure that both the rack and bowl are approved for use in the Instant Pot.)
Fill the bowl with potatoes and ¼ cup water.
Close and lock the lid.
Set the pressure valve to Sealing.
Cook on manual / high pressure for 6 minutes.
When done cooking, leave the machine on Warming (most machines automatically revert to this after cooking). Allow pressure to release naturally for 10 minutes. (Tip: I like to set a kitchen timer so that I don’t get distracted and forget.)
Manually release any remaining pressure.
Carefully remove the bowl of potatoes and rack.
Drain potatoes and let cool for a few minutes. When potatoes are cool enough to handle, slice in half. Heat a skillet with 1 tablespoon oil over medium heat. Add potatoes and saute until golden brown, 5 to 7 minutes. Season with some salt and pepper.
Toast hamburger buns.
Fill buns with Sloppy Joe filling (it will be messy!). Serve with home fries on the side.