Clean the mussels: Go through each mussel to see if they are alive. If the shell is fully closed, they are good. If a shell is fully open or cracked, discard. If a shell is partially open, tap it gently or close with your fingers and if it moves on it's own or stays closed, it is good. Rinse mussels under cold water and scrub any debris from outside of shell. Place in cold, heavily salted bowl of water for at least 20 min. Drain and rinse again with cold water. Heat olive oil in skillet on medium heat. Add garlic and cook one min until fragrant. Add tomaotes and clam juice. Stir and cook for 5 min. Add parsely and red chili flake. Carefully add mussels to pan. Add fennel. Turn heat down to medium low. Place lid and steam for 5 minutes. Check mussels. If they are not fully open, cook additional 2 min. Discard any unopen mussels. Serve in large bowl, topped with broth.