"I was not feeling well one evening and wanted soup. But I only had chicken broth and that sounded boring. I'd made egg drop soup before and thought that sounded perfect, so I started looking up recipes. Since I couldn't quite make any of the ones I found, I combined them to make this. It helped settle my stomach and was super easy to make. Garnish with crushed peanuts, chives, chili sauce, red pepper flakes, and lime wedges."
Combine chicken broth, soy sauce, and sesame oil together in a small saucepan; bring to a boil. Stir udon pieces into broth and cook, stirring occasionally, until cooked through but are still firm to the bite, 10 to 12 minutes.
Whisk water and cornstarch together in a bowl. Whisk cornstarch mixture into broth mixture until smooth and thickened slightly. Gradually pour in eggs, stirring gently and constantly, until eggs are wispy and cooked through, 2 to 3 minutes. Season with sea salt and black pepper.
Be careful to keep stirring the soup while you add the egg or it will clump up. Stir briskly if you're worried about this. Over-stirring is not as much of a problem as under stirring.
I like to have wheat toast with this, since it is not very heavy.