In saucepan, bring 1 cup/250 mL water, wine, celery, parsley stems, bay leaves, black pepper and salt to boil; add mussels and cook, covered, until shells open, 2 to 5 minutes. (Discard any unopened mussels.) Reserving liquid, strain into saucepan.

When cool enough to handle, remove mussels from shells. Add enough water to reserved cooking liquid to make 5-1/4 cups/1.3 L;bring to gentle simmer and maintain over low heat.

In separate saucepan, heat oil over medium heat; fry onion, garlic, anchovies and hot pepper flakes until onion is softened, about 4 minutes. Add rice; fry, stirring, until rice has absorbed fat and grains are translucent with white centres, about 3 minutes.

Add 1 cup/250 mL of the mussel stock; cook, stirring constantly, until liquid is absorbed. Repeat with another 1 cup/250 mL stock. Stir in tomatoes and oregano; return to simmer. Stirring almost constantly, continue adding stock, 1 cup/250 mL at a time, until rice is creamy and tender yet slightly resilient, 18 to 20 minutes.

Stir in mussels, flat-leaf parsley and 1/4 cup/60 mL stock; stir until mussels are heated through, about 1 minute. Serve immediately.

Makes 4 servings.