I threw together a pretty mean seviche last night! The tomatoes at the store were crap so I cheated and used a can of diced toms with habanero peppers, that worked very nicely.
1 lb bay scallops
1 lb shrimp (I don't specify size- if they're large, cut them to about the size of the scallops)
6 limes, juice of
6 lemons, juice of
1/4 C Orange juice (no sugar- as close to pure real OJ as possible)
1/2 C diced fresh Roma tomato (or rough amount canned)
1/4 C finely diced cucumber
1 TBSP minced pepper (habanero, jalepeno, etc- however much warmth you like)
1 TBSP fresh cilantro, roughly chopped
1 TBSP Italian parsely, roughly chopped
Sea Salt (to taste)
Freshly ground black pepper (or peppercorn melange, to taste)
Place the shrimp and scallops in a mixing bowl. Add the herbs, then the tomatoes and cucumbers, stirring to mix well. Hit the mix with a little bit of S&P, but not too much. Once the ingredients are well mixed, add the lemon, lime & orange juices. Stir to be sure all the seafood is in contact with the marinade; this is important as the acid in the juice will "cook" the seafood.
At this point, transfer into a storage container with a lid. Ideally, use a deep-ish steep walled container like a commercial Cambro- the idea is let the stuff sit in the juice. Refridgerate for at least four hours, and overnight is better. If you aren't going to eat all the ceviche at once it's best to drain off the juice after the 8 hours or so has elapsed. Leaving the seafood in there indefinitely will make it mushy as if it was overcooked.
Serve with chips or crackers for dipping, or with leaf lettuce for roll-ups. And it's hard to beat a Caesar salad with a heaping scoop of seviche!