Heat the olive oil in a large pot and cook the leek, fennel, bacon and garlic cloves for 5 mins.
Add in the cherry tomatoes and cook for 5 mins until soft and pulpy
Mix in the fish stock and bring to the boil before quickly adding in the fish chunks and mussels. Cook for 5 mins until the fish chunks are cooked through.
Add the zest and juice of half a lemon and season with salt and pepper.
Discard any mussels that did not open, and ladle into bowls topped with parsley, lemon wedges and served alongside some bread.