How to cook Roast Beef or Pork Roast in a Pressure Cooker.

I love roast beef (and pork roasts too!), Using my pressure cooker gets them done fast and with great flavour. 3-4lbs Pork or Beef Roast 3-4 cups potato 1 onion 1 cup carrots and/or Butternut squash 1/2 cup corn 1/2 cup peas 1 1/2 cups beef broth 1tbsp cornstarch 1tbsp garlic minced salt, pepper, rosemary Worcestershire sauce