1. Bring a pot of water to the boil and add fettuccine and cook till al dente. 2. Debeard and scrub mussels if necessary. 3. Heat large pot and Sweat diced onion and garlic. 4. Add limejuice, wine and ¾ cup of water, bring to boil. 5. Add mussels and cover to steam to open. 6. As the mussels open take them out. Throw away any mussels that don't open. Cover with alfoil while you finish the sauce. 7. Bring the remaining liquid to the boil, add cream and simmer for 2-3 minutes. 8. Return the mussels to pot and toss through sauce. Serve over fettuccine.