Scrub mussels thoroughly, discarding any cracked or opened shells. Saute garlic in hot olive oil in a Dutch oven over medium-high heat until tender. Add wine and bring to a boil; add mussels, cover, reduce heat, and simmer 3 minutes or until mussels open. Immediately remove opened mussels with a slotted spoon to a large bowl. Continue cooking remaining mussels 2 minutes; others may open. Discard unopened mussel shells, reserving broth. Bring broth to a boil; reduce heat and simmer 5 minutes. Stir in tomatoes and green onions and cook about 30 seconds; add mussels and toss just to reheat. Sprinkle generously with freshly ground pepper; garnish with fresh parsley and additional green onion slices, if desired. Serve with crusty French rolls.