Okay... I have to hit the fish part first... because NOTHING else (food wise) is worse than ill-cooked fish. Not even spoiled food. Because fish can be soooo fantastic, it's like having bad sex to eat ruined fish. I dated a fishing guide for 2.5 years, and ate fish 6 nights out of 7. There is a LOT one can do with fish... but the SECOND most important step is not making it inedible by cooking it badly.
FIRST: Picking your fish.
Ideally, buy your fish from a monger. Grocery stores in general are to be avoided like the plague (I swear, I think Albertsons stores their fish in old tires. Kroger has freezer issues. And I could go on. Ick. The only chain store I have ever come across which treats their fish with the respect it deserves is WholeFoods. But that is reflected in the cost. From the boat to the processing plant to shipping, treating fish the way it needs to be treated (to be good) is EXPENSIVE AND TIME CONSUMING. Fishmongers buy local more often than not (often caught that day), and they work on a small scale which keeps their costs down. So it's usually half as expensive to buy from them as opposed to WholeFoods. But I live 5 minutes away from wholefoods, and 30 from the fish market, so that's where I buy.
Once you're at a place that has good fish to start out with... the next tip/trick is purchasing it.
1) Ask what's good. This will change on a day to day basis. As you get used to seeing "good" fish, you'll notice the very subtle differences that tell you that the rock cod is phenom right now, or the salmon should be passed over this week but would still taste okay. You'll walk in and go "Ooooooh! The trout is *gorgeous* today!". It's just like picking red meat. You get used to what looks great, okay, iffy, and 'my god... they're actually SELLING that???" Number 1 BIG hint: "Fishy" is what fish smells like as it's starting to decay. Fish shouldn't smell like fish. It should smell like fresh water or salt water. AKA have almost no smell. If it smells fishy, acidic, or 'beachy', don't buy it to begin with, and if you mistakenly DO buy it (or it sits in your fridge for longer than 36 hours) toss the sucker to the cat. NO fish store or section should smell fishy or acidic. If you can smell their fish from 5 feet away... don't walk, but RUN out of the store. Gross. (Ahem! Albertsons!!! Take note!)
2) Cut. Cut is as important with fish as it is with meat. Avoid steaks in general. "Steaks" have bones, bloodvein on BOTH sides, and skin. Restaurants go to EXTREME effort to serve steaks (worked in a 4star in highschool as a cook/apprentice). Rather like a wedding dress they completely and totally deconstruct the steak (to remove skin, bloodvein, and 2/3s of the bones... cook fish seperately, sear the skin, and then put it all back together. "Steaks" sounds good to red meat eaters, but it's part of the reason red meat people tend to not be fish people. With everything EXCEPT Tuna, you want FILLETS, and you want them to skin it for you (unless you have a wicked fillet knife and the time to learn how to do it in less than 10 minutes... and that's just practice). On TUNA (which I don't like cooked in general, but we'll skip over my prejudices) you want a WEDGE. Tuna is a weird fish. It has these long triangular wedges... kind of like a pork loin. You buy however many inches/pounds of wedge you want, and then you cut it into 1/2-3 inch triangles, either before cooking or after (like for seared tuna.. you sear the outside of the wedge, and then slice it into thin triangles).
3) When you buy a fillet... look for the dark stipe. Every fish has it. It's usually a darker colored stripe than the meat itself, sometimes a light greyish brown, sometimes it's bright red (on some white fish). This is the fish's "blood vein". It's not a vein. It's a channel that runs THROUGH the muscle and it filters their poop and rancid oils. Yeah. POOP AND RANCID OILS. Yum. :P cough gag cough :P. Good fish mongers will have cut their fillets to avoid the blood vein whenever possible, and then will have cut any that is on it OFF. Even good chain stores, like WF, cut 'normal' fillets, with the stupid strip right down the middle of the fillet. Why? Because it adds weight to your purchase. You end up with a lot more "scraps" as well cutting fish into vein free fillets. Mongers use those scraps, stores toss them. Meaning even less profit. BUT each and every single filet is going to have more or less blood vein than other fillets. PICK YOUR FILLET. The seller will know you for a fish person when you say "I want that one, and this one over here, and can I see that one? (hidden under others), Okay, not that one. That one? Yeah... lets do that one."
3) Okay. You've gotten your fillets home. Now it's time to cook them. Because you want to cook them the same day you've bought them. Period. If you bought 'caught that day' fish, you can cook it tomorrow. Never the day after. If you bought regular fish, you need to cook it within a few hours. Trust me. MAJOR taste difference.
3.5) If you have a GOOD seller... They'll remove the blood vein for you before you came home. Most don't. As in they're not allowed to.
4) Time to remove the bloodvein. Ideally, before cooking. It's much EASIER to remove it after cooking (and I'll do that when I'm short on time)... but the fillet will be steamed in some of the fish oils and poo... so you really don't want to. If you HAVE to cook it with the blood vein in... make sure it's on the top... so the evaporating poop and oils go upward into the air, instead of upward through the flesh of your fish. The halfway cheat is to sear it for about 30 seconds ON the bloodvein side, grab a spoon, and scrape that grey nastiness off and throw it away. Like I said, FAR easier when cooked to remove it. Comes off with a spoon scraped gently down it. To remove it ahead of time take a VERY sharp knife and cut it out (if you don't have a bendy fillet knife... just fold the fillet so that the bloodvein is the buldgy part and cut it off that way OR just cut on either side of the bloodvein. This wastes a lot of fish. I only recommend it if you have a cat.
5) COOKING TIME :) :) :)
a) Fish, of all types, cooks very very quickly. To be "done" it only needs to be opaque and flaking. The ONLY reason any fillet should take longer than 5 minutes (and most only take 2 minutes) is if you're braising it in a sauce (like a ginger garlic cream sauce, or a coconut curry... neither are low calorie dishes). Cook it on HIGH temps (sautee or Broil or BBQ... never, never, EVER bake fish. It's like baking a steak. And remember, if it takes longer than 5 minutes, you've overcooked it. On high heat a 2 inch thick fillet takes about 2.5 minutes per side max. Most people don't buy 2 inch thick fillets, becuase very few fish have muscle that thick.
b) GOOD fish, with no bloodvein and no skin, needs almost no seasoning. People put lemon on fish because it breaks apart some of the rancid oils so they don't cling to your tongue. Gross. Right? Or to cover up the decaying fishy flavor (the oils start decaying first, so the acids in citrus really help the taste of decaying fish) The only thing you "need" for good fish is salt, pepper, and a little bit of oil... and you will have melt in your mouth restaurant quality fish.
c) from that restaurant quality melt in your mouth base you can PLAY. Sauces, oils, herbs, garlic, curries... the list is never ending. But trust me, trust me, trust me... cook it 'plain' first... take a bite and then add whatever you want. Drizzle it over, sprinkle it over, have FUN. Three of my current favorites are halibut drizled with chimichurri sauce (an Argentine green sauce made with parsley, cillantro, garlic, and a dash of lime... it's actually BEST on red meat, but I've been on a binge lately, and just love it on halibut), snapper with a creamy avacado sauce (in a taco), and salmon with a miso/soy/aji mirin sauce. But SERIOUSLY... PLAY. Herbs de Provance, Watercress, teriyaki, pick an herb or herb blend... pick a sauce, and just PLAY.
d) exceptions that prove the rule are braising or wrapping or smoking or steaming options. These are the LONG cook time fish that you really want to absorb the flavors of what you're cooking it on. Like Alder Planked Halibut, Ginger Garlic Cream Sauce BBQ salmon (you make the sauce, let it cool, pour it over the raw fish in a homemade tinfoil container, and bbq on low heat for 30+ minutes), or potato wrapped chilean sea bass. NOT curries, however, because with curries, you cook the fish and then add it to the curry.
6) REHEATING = DON'T. Well, you can, but probably not at work. Because to reheat fish, the only way to do it without ruining it is to use a stove and either quick sear, quick broil, or reheat the sauce/ curry/ etc. and pour it over the fish. UPSIDE: Nearly all good fish is good COLD or at room temp. If you're using a sauce or curry, reheat the sauce in the microwave to way too hot to eat (and any side) and add THAT to the cool fish. Let it sit for a few minutes and both will come out warm. But far better (imho) is to just eat the cold fish. Try mixing it up from dinner the last night by having a DIFFERENT sauce. Like a tempura dipping sauce, or toss it in a flour tortilla with some pico de gallo or avacado cream sauce and some veggies.
AND for some absolutely PHENOM/ easy easy easy recipes... check out Italy's Bible. It used to sell for over $100. It's now $30 from Amazon. The Silver Spoon.