Nutrition: per serving
Clean the mussels, removing their beards and discarding any that are broken or do not close when tapped on a worksurface. Put a large pot over a medium-high heat. Add the olive oil and cook the onion until soft.
Add the garlic, bay, saffron and peppercorns, and stir for a minute. Add the tomatoes and fennel sprigs, stir for another minute, then pour in the ouzo and the hot stock. Cover and bring to the boil.
Add the mussels, cover and cook for 5 mins until they open – discard any closed ones. Using a slotted spoon, transfer the mussels to a plate, strain the cooking liquid and keep it warm. Set aside 12 mussels for serving. Remove the remaining mussels from their shells and set aside, too.
For the orzo, put a large, deep, lidded pan over a medium-high heat. Add 3 tbsp of the olive oil and lightly toast the orzo for a couple of minutes until slightly golden. Transfer the toasted orzo to a plate. Return the pan to the heat and add 1 tbsp of olive oil. Fry the onion until soft and glossy. Add the garlic and pepper, and stir for a couple of minutes. Add 900ml of the reserved mussel cooking liquid to the pan and bring to the boil. Add the orzo back in and gently stir. Cover, reduce the heat to medium-low and gently simmer for 15 mins, checking occasionally and stirring, until most of the liquid has been absorbed. Mix in the shelled mussels and chopped fennel fronds. Season with pepper, garnish with the reserved mussels in shells, drizzle with a little olive oil and serve immediately.
