People can be squeamish about fish.  I used to work in the seafood department of a supermarket and frequently fielded such head-shaking questions as, "Does it smell like fish?" or my favorite, from a woman standing in front of a tank of lively rainbow trout, "Are they fresh?"

Don't fear the fish.

The truth is fish are among the most versatile, healthy and easy to cook proteins available to us.  Grill it, fry it, poach it, flash-cook it -- it's quite hard to screw it up.  Hell, you can even stick it in the oven still frozen and have it turn out great.  But it's hot, it's humid, and it's DC, so we're all about no-heat meals right now.  Which brings us to the next Escape the Heat recipe:  Ceviche.

Technically, ceviche is not cooked, per se, because the process doesn't use heat.  But the citric acid marinade denatures the proteins in the fish enough to change the texture and appearance.  Read this for a brief but more comprehensive explanation of this process, along with some alternatives if you're still a little undecided about raw fish.  If you'd like to try ceviche professionally prepared before attempting it on your own, I highly recommend Oyamel, which serves some fantastic varieties.

Your basic components are fish, acid and seasonings:

Fish 

Use a firm fin- or shellfish, the freshest you can find.  Tuna, mahi mahi, snapper, grouper.  I like wild salmon, such as sockeye, sliced thin.  For shellfish, scallops, shrimp and crab all work well.  Or any combination of these.

Cut or slice the fish in bite-size pieces.  If the shrimp are small, shell and tail them and leave them whole.  Scallops may be sliced or chopped.  If you use a combination of fish, just make sure they're uniform in size, since they're all "cooking" together.

Acid

Lime juice is key.  (Again with the limes!  I can't say it enough:  a well-stocked summer kitchen needs a lot of limes!)  Some people also use lemon and/or orange juice, or a combination of the three.  How much?  For about a pound of fish, you'll need at least a 1/4 cup of juice, maybe a little more.

Seasonings

Onions:  usually red, maybe shallots, too, if you like. One onion should do it.

Cilantro:  a good-sized handful, chopped, with stems.  Then add some more.

Jalapenos, one or two, minced, with the pith and seeds if you like heat, without if you don't.

Sea salt, to taste.

Other options:  tomatoes or tropical juicy fruit like pineapple, mango, papaya.  It's really hard to screw up the ratios, so if you feel like being more liberal with the onions or jalapenos, go for it.  The only ingredient you need to make sure you have enough of is the citrus juice.

Method

Mix the lime juice with the seasonings , or grind the seasonings first in a mortar and pestle (or my version:  a Pyrex measuring cup and the handle-end of a citrus reamer) if you want to really bring out the flavors before mixing them into the juice.  Spoon a little of the mixture in the bottom of a nonreactive baking dish (i.e. glass, ceramic or Pyrex), layer the fish on top and add the rest of the juice/seasonings.  If you're using a small dish, layer it like lasagna, alternating between fish and juice.  The fish does not need to be swimming in the marinade, or even completely covered, although you will need to turn it partway through the cooking time to ensure all fish has contact with the juice.  Cover the dish with plastic wrap and store it in your fridge. 

So how long do you let it marinate?  It depends on the size of the fish, but a couple of hours will do it.  You'll notice a whitening of the fish as it "cooks," or in the case of already-white fish, an opaqueness will develop.

Do not let it sit for too long, however, because it is possible to overcook it, which renders it tough and chewy, just like if you used too much heat.

Serve it up!

The easiest method is to simply serve it in a bowl.  If you want to be authentic, toss in a handful of popped popcorn.   But ceviche also makes great tacos:  fill a corn taco shell with a little shredded cabbage or lettuce, sliced avocado, maybe some fresh corn, too?

Provide your version in the comments:  what's your favorite fish?  What ingredients do you use?  How do you like to serve it?