How to Make It
In a small bowl, blend the butter with the miso. In a large pot, heat the olive oil. Add the garlic and cook over moderately high heat until golden, about 1 minute. Using a slotted spoon, transfer the garlic to a plate. Add the crushed red pepper and saffron to the pot. Add the mussels and cook, stirring, until the shells begin to open, about 2 minutes. Stir in the sake and pastis. Add the water and miso butter and cook, stirring, until the mussels have opened and are coated with sauce. Discard any mussels that don't open. Stir in the herbs and garlic and serve in bowls with crusty bread.