Whisk together Gravy ingredients and set aside..
Use a Food Processor to make the Steak Patties by adding all ingredients, except ground beef and processing until chopped fine and combined.
Remove from food processor into a bowl, and add ground beef, stirring until well combined. Or add ground beef directly into food processor (if large enough), and use the pulse function of the food processor and pulse until combined.
Use your hands to Shape Beef Mixture into 6 oval, flat patties.
Pour 2 Tablespoons of Cornstarch onto a plate, and carefully dredge your patties in the cornstarch until coated on all sides. Set aside.
Using your Instant Pot, select Sauté function, once it displays “hot” add oil and swirl to coat bottom and then add 2 Tablespoons Butter.
Working in batches, place patties into the cooking pot of the now hot Instant Pot, directly into the oil and butter mixture, sear on both sides and remove to a plate. Cook only 1-2 at a time to avoid breaking patties when removing from the pan.
Once you have browned the outside of the patties, add the remaining butter to the pan, and use a wooden spoon to scrape any brown bits off the bottom so you do not get a burn notice. Once you have it scraped well, add in mushrooms, onions, and minced garlic, and cook 2-3 minutes, until onions are fragrant.
Then add red wine or beef stock and use the wooden spoon to scrape the bottom of the pot again, deglazing the cooking pot with the wooden spoon to scrape up any stuck on brown bits off the bottom. This is very important to do, or you will get a burn notice on your pot.
After deglazing, continue cooking until Onions are soft, another 2-3 minutes. Then add in the gravy mixture you stirred together in the first step, and stir to combine it all.
Carefully, place your seared Beef Patties into cooking pot into the gravy mixture. Do this carefully so they do not fall apart.
Put lid on, and lock into place, set pressure valve to “sealing” and cook on high pressure for 4 minutes. After 4 minutes is up, let pressure naturally release for 10 minutes, then quick release remaining pressure.
Remove Steaks/Patties from the pot, and turn pot “off”.
Then press the Saute button, and simmer the gravy to thicken. While it simmers mix together 3 Tablespoons of cold water and 2 Tablespoons of corn starch to form a slurry, then add that into the pot, and stir. bSimmer for 2-3 minutes to let the gravy thicken.
Taste gravy, season with additional salt and pepper if necessary.
Serve with gravy spooned over steaks/patties, and over mashed potatoes, and garnish with fresh parsley