Rinse fresh PEI Mussels under tap water. Tap any mussels that are still open and discard any that do not close after being tapped and rinsed. Set aside.
In large shallow pan, melt butter over medium heat; cook chopped onion, tomato, salt and pepper, stirring occasionally, until softened, about 5 minutes.
Squeeze juice from lemon into pan; add remaining lemon. Add beer; bring to boil.
Add mussels, cover and simmer until mussels open, about 10 minutes. Discard any that do not open. Discard lemon; sprinkle with green onion
Recipe source:
adapted from www.canadianliving.com