Suppose I told you to buy some "very fresh" fish, chop it up and serve it raw. Raise your hand if you'd be comfortable doing that? I have a feeling very few hands went up. So, let's go over some basics of serving fish raw
1) Mitigating the bacteria risk:
Buy your fish from a reputable market that has good turn over. Here is all you need to know about finding such fish market and buying fish. Great fish markets might be hard to find in some parts of US, but if you are in a large coastal city (Boston, New York, San-Francisco, Seattle, etc), you have that option even if you haven’t discovered it yet. If you are in Boston, go to New Deal. Tell your fishmonger you plan on serving fish raw and ask what they recommend. Fish you can use for this dish are branzino, hamachi, kampachi, hiramasa, arctic char, and
May 3 update: Farm-raised salmon turns out not to be as parasite free as I thought when I wrote this post. I suggest freezing it for 7 days before using, or using arctic char instead.
2) Mitigating the parasite risk:
If you bought fish that is farm-raised in closed-circle system (branzino, arctic char, hamachi, kampachi) or large wild tuna (yellowfin, bluefin, big-eye), you can use them as is. If you use any other wild fish or farm-raised salmon, you'll need to freeze the fish for 7 days to kill potential parasites (that is if you want to completely eliminate the risk of a parasite infection). To freeze your fish, remove the skin from the fillet, wrap it as tightly as possible in plastic wrap and freeze for 7 days. Move it to the fridge 24 hours before using. Keep in mind that only fatty fish freeze well. Lean fish (halibut, cod, fluke, etc.) turn to mush after freezing, so it's best to avoid them in raw preparations.
May 3 update: I updated section 2. Originally, I was suggesting that all farm-raised fish are safe to eat raw without freezing. That turns out to not be completely true. Fish farmed in the ocean (such as salmon) have a lower risk of parasites that their wild counterparts, but it's not insignificant.
3) Preparing the fish:
Since branzino is usually sold whole. Each fish is about 1 Lb, yielding 1/2 Lb of flesh you’ll need for this dish. Ask your fishmonger to fillet, skin, and debone it for you. He or she is much better at it than you are; it’s a free service at most fish market. Salmon, and kampachi are usually sold filleted with the skin. You can ask your fishmonger to remove the skin, or you can skin it yourself.
That's all there is to it. You are ready to make tartar.
The key ingredient in this dish (besides excellent fish) is knife skills. This is a great opportunity to perfect your brunoise. Brunoise is a vegetable cut of 1/8 inch dice, in other words very small. Cut your apples and onions any bigger, and the dish loses its fine texture and elegance. Use a food processor, and you got yourself a mush resembling baby food. Small amount of crunch is essential to this dish, so you've got to sharpen your chef's knife and be a little patient. But once you are done chopping, you are only 1 minute away from one of the coolest raw fish dishes.
Branzino Tartar with Apples and Ginger
Fish substitutes: kampachi, salmon
Note on apples: you need an apple with good acidity, so stay away from red delicious (they taste absolutely awful anyway). Granny Smith is the most widely available variety, but if you are making this dish in the fall, look around your farmer’s market for Northern Spies, Honey Crisp, or Cortland.
Serves 2-3 as an appetizer
1/2 Lb skinless, boneless branzino fillet, cut into 1/4 inch dice
1/4 cup diced tart apple (1/8 inch size dice)
2 Tbsp diced red onion (1/8 inch size dice)
1 tsp finely minced ginger
1 Tbsp finely minced cilantro, mint, or dill
2 tsp fresh squeezed lime juice
1/4 tsp Dijon mustard (optional)
2 tsp olive oil
1/4 tsp kosher salt or to taste
Freshly ground black pepper to taste
Combine all ingredients together and mix well. If you want the restaurant presentation, place ring molds onto serving plates. Pile in tartar, and then lift off the ring molds. Well rinsed tuna cans, with top and bottom removed, make excellent home-made ring molds.
Correction note on 10/22/06:
The original post listed fluke as one of the fish you can use in this dish. After defrosting a piece of fluke this evening, I must advice against using it unless you are willing to eat it without freezing (thus taking a small parasite risk). It turned into an absolute mush after I defrosted it. I suspect this was due to fluke having absolutely no fat and very high water content. Branzino on another hand froze and defrosted quite well without losing its texture.