Broccoli Cheese Soup

Put a soup pot over medium heat. Add vegetable oil and onions and cook for 4 minutes, stirring often. Add the frozen broccoli and continue stirring for about 5 more minutes until the onion in translucent and the broccoli is thawed. Add half and half and water, and bring to a slow boil. Add Velveeta, salt, pepper, and garlic powder. Cook at a slow boil, stirring often until cheese melts. Mix corn starch and cold water in a small bowl. Add to cheese mixture and cook until the soup thickens.