Saute the onion and garlic in oil until tender. Add the tomatoes, chicken stock, wine, oregano and tomato paste. Bring to the boil, reduce the heat and simmer for 30 minutes.
While the sauce is simmering, scrub the mussels under cold water and remove beards. Bring the sauce to the boil, add the mussels, cover and simmer for 5 to 7 minutes or until the mussels open. Sprinkle with parsley.
Serve with garlic or herb bread. Yum!