When making ceviche, the quality of the scallops makes all the difference, so be sure to buy fresh (not frozen) scallops. There is no cooking involved; the raw scallops will "cook" in the lime juice in just one hour (less time and the scallops will be too raw; more time and they'll get mushy). When scallops are in season, the combination of the briny scallops, citrusy lime juice and all those fresh vegetables make this a great appetizer.
Technique tip: For flavor without overwhelming heat, just use the flesh of the jalapeño. Cut it in half lengthwise and remove the seeds and ribs before mincing. The oils will get on your hands; be sure to wash them afterward!
In a medium bowl, combine the scallops, 1/2 cup of the lime juice and 1 teaspoon salt and set aside at room temperature for exactly 1 hour, stirring occasionally.2.
In a separate bowl, combine the cucumbers, shallots, scallions, avocado, bell pepper, parsley, jalapeño pepper, and garlic. In a glass measuring cup, whisk together the remaining 1/4 cup lime juice, 1/4 cup olive oil, 1 teaspoon salt, 1/2 teaspoon pepper and the Sriracha. Pour over the vegetables and combine.3.
When ready to serve, lift the scallops out of the lime juice with a slotted spoon (discard the liquid) and add them to the vegetable mixture. Stir well and spoon into the lettuce leaves for serving.