Elise Bauer of Simply Recipes writes,

The first time I made ceviche, I was amazed. I could actually see the lemon and lime juice turning the color of the fish from translucent pink to opaque white. The acid from the limes and lemons change the structure of the proteins in the fish, essentially "cooking" the fish without using heat. I love ceviche rolled up in a freshly cooked, still warm corn tortilla with lettuce and salsa.

This simple, clear fish dish can be made, according to commenters, with swordfish, tuna, shrimp, scallops and other shellfish, octopus, cod, sea bass and more. And they chime in with their own variations, ranging from mango to whiskey. (Elise made it with red snapper.)

Leave it to marinate no longer than six hours, they warn, lest it turn to mush.

Here you go: Ceviche Recipe