How to Make It
In a glass bowl, toss the scallops with the lime juice. Cover and refrigerate for about 45 minutes, stirring occasionally, until the scallops just start to turn opaque.
Meanwhile, in a blender, combine the jalapeño with the chopped cucumber, garlic, cilantro, parsley, mint, oil and water and puree until very smooth. Season the aguachile with salt.
Pour off all but 2 tablespoons of the lime juice from the scallops. Add 3 to 4 tablespoons of the aguachile to the scallops and mix well; reserve the remaining aguachile for another use. Fold in the onion and the thinly sliced cucumber and season with salt. Spoon into bowls or glasses and serve with tostadas or tortilla chips.