Scrub live mussels under cold running water. Pinch the beards that are visible between the shells and pull to remove. Combine 4 quarts cold water and 1/3 cup of the salt in a large bowl. Add mussels and soak for 15 minutes; drain in colander and rinse. Repeat twice more, using fresh, salted water each time.
Melt butter in a large saucepan or 4-qt. Dutch oven over medium heat. Add green onions, jalapeno peppers, and garlic. Cook and stir for 1 minute. Carefully add broth; heat to boiling, reduce heat and simmer, covered, for 10 minutes. Add mussels. Cover and cook for 6 minutes or until mussels open. (Discard any mussels that do not open.)
Meanwhile, stir together finely chopped tomato and lime peel; set aside.
Transfer mussels to shallow bowls using a slotted spoon. Stir whipping cream into cooking liquid. Bring to boiling; reduce heat. Boil gently, uncovered, until reduced to 2/3 cup (about 5 to 7 minutes). Add tequila to sauce; heat through. Spoon sauce over mussels. Serve immediately topped with tomato-lime mixture; pass lime wedges. Makes 4 to 6 appetizer servings.