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 use the pulse function of the food processor and pulse until combined.
Shape Beef Mixture into 6 oval, flat patties. Dredge beef patties with corn starch, and shake off any excess.
Select Sauté function on Instant Pot, and once it displays “hot” add oil and swirl to coat bottom and then add 2 Tablespoons Butter.
In batches, place patties into cooking pot, 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.
Add the remaining butter, mushrooms, onions, and minced garlic, and cook 2-3 minutes, until onions are fragrant.
Add red wine or beef stock and deglaze cooking pot by using a wooden spoon to scrape up any stuck on brown bits off the bottom.
Continue cooking until Onions are soft, another 2-3 minutes.
Pour Gravy mixture into cooking pot and stir to combine.
Carefully, place seared Beef Patties into cooking pot.
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. If in a hurry, remove 1 cup of liquid and add 2 Tbs of corn starch, and whisk together to form a slurry, then add back into the pot, and simmer for 2-3 minutes.
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