In a large bowl, combine the ground meat with the egg, bread crumbs, onion powder, garlic powder, basil, oregano, thyme and worchestershire sauce.

Form 8 patties.

Preheat the pressure cooker by pressing the saute button.

Place the olive oil into the pot.

When the unit is hot, add the patties, two at a time and brown on each side.

Set the patties aside.

Add the sliced onion to the pot and saute until the browned bits release.

Add the mushrooms to the pot and saute another minute.

Place the patties on top of the onion and mushrooms.

Pour in the beef stock and add the garlic and balsamic vinegar.

Place the lid on top of the unit and close to locked position.

Turn the steam vent to closed position.

Press the keep warm/cancel button.

Press the manual button and adjust the time to 12 minutes.

When the unit has pressure cooked and counted down to zero, carefully release the steam.

Remove the patties, onions and mushrooms and place into a dish.

Press the saute button.

Combine the corn starch and cold water.

Once the liquid in the pot begins to boil, whisk in the cornstarch mixture.

Season with salt and freshly ground black pepper to taste.

Turn the unit off and pour the gravy over the salisbury steaks.