1. Steam spinach with sugar until soft. Pour immediately into a colander, running cold water over the spinach. Squeeze spinach leaves to extract as much moisture as possible.
2. Beat egg whites with water until smooth but not foamy.
3. Mix cornstarch with 1/3 cup broth.
4. Heat remaining broth in a pan over high heat. Bring to a boil, and then turn heat to medium. Add ham and cook for 5 minutes. Turn heat to high and add spinach, stirring until it boils.
5. Season soup with salt. Restir the cornstarch mixture and stream it into the soup, stir until thickened.
6. Remove pan from the heat and whirl in the egg white. Wait 30 seconds then stir to mix, adding sesame oil and vegetable oil.
7. Serve immediately.