Begin by cleaning the mussels under cold running water. Remove beards and any debris, ensuring only tightly closed mussels are used.

While the mussels dry, finely chop the onion, garlic, and tomato.

In a large pan over medium heat, combine vegetable oil and sesame oil. Add the chopped onions, minced garlic, and grated ginger. Sauté for about 3 minutes until soft.

Stir in white miso and chopped tomato. Cook for an additional 2 minutes.

Pour in vegetable or chicken broth, fish sauce, and mirin. Stir well and bring to a boil.

Add cleaned mussels to the boiling broth. Cover the pan and steam for 8-10 minutes until mussels are opened.

Once cooked, stir in cooking cream and unsalted butter to finish the broth.

Serve mussels in bowls with broth, top with finely chopped chives and chili oil, alongside toasted crusty bread.