Remove beard and clean mussels well with a toothbrush under running water.

In a pot, heat oil and sauté the onions, garlic and ginger. Add tomato if desired, I prefer none to keep the sea taste in the soup. Mash in pot.

Once onions are translucent, place 1 cup water and bring to a boil. Once boiling, drop in mussels, add enough water to reach the mussels on top of the pot (water would depend on your pot size. Less water = more flavour). Season with drops of fish sauce. Sprinkle some fresh ground pepper. Cover.

Simmer until shells open. Remove any scum rising to the top. Taste and adjust according to desired saltiness and ginger spiciness- use fish sauce, salt, pepper, drop in chili, if desired, add more ginger if needed. Simmer 3 minutes more.

Discard shells that did not open. These were dead when they were bought, and unsafe to eat.

Add spinach or pepper leaves if desired. (None added in photo) Garnish with chopped green onions. Stir. Turn off heat and cover to cook leaves in residual heat. Serve and enjoy.

Optional step: Add the secret ingredient before the veggies- gives it a sweetish taste.