Wash and clean the tahong thoroughly. Boil the mussels until cooked, then remove the meat from the shells. Set aside while preparing the other ingredients.

Heat the cooking oil in a pan over medium heat. Add the garlic and sauté until fragrant. Add the onion and cook until softened.

Add the sliced tomato and continue cooking until the tomato becomes tender and releases some of its juices.

Put the cooked tahong into the pan and stir gently to combine with the sautéed ingredients. Add the fish sauce and mix well.

Pour in the water and add seasoning granules if using. Bring the mixture to a boil.

Add the odong to the boiling broth. Cover and cook for about 5 minutes, or until the noodles are tender.

Add the misua and cook for another 5 minutes. Stir gently so the noodles do not stick together.

Taste the soup and adjust with salt and ground black pepper as needed. Keep in mind that the fish sauce already adds saltiness, so add salt gradually.

Add the chopped spring onion and allow it to cook briefly. Turn off the heat once everything is fully cooked.

Serve the soup hot and enjoy.