Fry the eggs sunny-side up in a little olive oil, seasoning them well with salt and pepper and leaving them rather runny. The eggs can be fried up to an hour ahead and held on a baking sheet at room temperature.
In a large pot, bring the chicken stock to a simmer. Add the garlic and simmer for 5 minutes. Add the ginger and cook for a few minutes more. Taste and add salt as needed.
Just before serving, add the spinach or bok choy to the hot soup. It will just take a minute to wilt.
For each serving, put a fried egg in a warmed shallow soup plate. Ladle over the hot broth and sprinkle with the scallions. Serve the soup immediately.