Combine water with ¼ cup lime juice in a medium saucepan and bring to a boil. Add the mussels, cover the pan and cook, shaking the pan occasionally, until the mussels have opened, about 6 minutes. Discard any mussels that do not open. Remove the mussels with a slotted spoon and place in a colander set over a large bowl. Reduce heat so that the cooking liquid is simmering, add the shrimp, and cook until they are opaque and curled, 30 – 60 seconds. Remove with a slotted spoon and add to the colander with the mussels. Add the calamari rings to the cooking water and cook until they turn opaque, about 1 minute. Remove calamari from the cooking liquid with a slotted spoon and add to the colander.
Place all the drained seafood in a large bowl; add the tomatoes, onion, jalapeno, and cilantro. In a small bowl stir together the remaining ¼ cup lime juice and the San-J Mongolian Sauce. Add to the seafood and stir gently. Serve immediately or refrigerate for up to 2 hours.