Using scissors, trim the shrimp tendrils. Rinse and drain very well.

In a pan over medium heat, heat oil. Add onions and garlic and cook until softened. Add fish sauce and cook for about 1 to 2 minutes, stirring regularly.

Add tomato sauce and allow to simmer until reduced and thickened. Add mussels, fish balls, and shrimp continue to cook, stirring to combine, until coated with tomato sauce and the color has turned pink.

Add oyster sauce and continue to cook for about 3 to 5 minutes or until shrimp are cooked and the sauce clings to mussels, fish balls & shrimp. Season with salt to taste. Serve hot.