Serious Eats - seriouseats.com

The one ingredient that's changed my cooking? The internet? Is that lame? Before I became a serious foodie, all I ever made were the simple and hearty dishes that my mother had taught me how to cook. Once I discovered Serious Eats and various other food blogs, though, the quality (and quantity) of the food I make skyrocketed. That's not to say that the dishes i learned on weren't good - just that my eyes have been opened to so, so, SO much more that I can't imagine getting recipes and tips anywhere else.

(And if I really really have to pick a food ingredient, I'd say good olive oil. I never truly appreciated how great quality olive oil can really imporve a dish's flavors.)

Chipotles chilies...they add so much wonderful flavor to just about any type of cuisine.

I would second the idea of good olive oil. So many great uses.

finally having the discipline to grow and sustain fresh herbs at home: basil, parsley, chives, rosemary, thyme, sage, dill, and tarragon.

Never could bring myself to buy them, so now having them available the last couple years has made food from the kitchen much, much better.

shallots. It's so simple, yet I never realized how such a subtle taste can take a dish to a whole new level. They're so versatile and I really love the color too!

zest! lemon, lime, orange... adds such a great flavor.

aged balsamic vinegar that's so sweet yet tart. i could eat it on most anything.

I'd have to say Greek yougurt. I use it in many ways.

salt, kosher or otherwise. how much or how little to use. it seems odd, but my mom never used salt in our family food because of health reasons (not mine). so learning to use salt properly has been an interesting journey.

Probably cumin. It's so much more versatile than many think. Also lemon juice has gotten me away from over using butter, and dressing my vegetables more simply.

Anchovies. They add depth and flavor to sauces, especially tomato sauce. (I think it's the umami)

Contest or no contest, this is a great question. My most recent revelation is Maldon flaked sea salt for finishing dishes. It's crunchy, not chemically-tasting and adds a great texture and boost of flavor to so much - even simply sprinkled on sliced tomatoes it's blissful.

I have to go along with others here who have said fresh herbs. We now have oregano, parsley, basil, rosemary, thyme, mint and bay leaves in our garden. Having them within steps of my kitchen is such a pleasure and it has made such a difference in our cooking.

Smoked Spanish hot paprika has been showing up in all kinds of dishes that I prepare, from savory to sweet, including chicken-filled appetizer pies and black beans and rice to chocolate zucchini cake and sweet biscotti. It's the new "secret ingredient" that I love to play with.

I'm going to have to go with kosher salt. My boyfriend and I created a drinking game based around Alton Brown's Good Eats: every time he adds a pinch of KS to something - drink!

I'm going to have to go with quality olive oil as well.
But shallots have to be a close second. I'm finding these to be required stock 'round my kitchen.

anchovies add depth into sauces that people cannot put their finger on but know it tastes yummy!

Learning how to properly season things using something other than table salt has made a world of difference.

This is going to sound odd, I'm sure, but the one ingredient that has come to mind is Italian Flat-Leafed Parsley. It adds so much brightness and freshness to a dish, I am angry with myself for ignoring it for so long. It's no longer "just a garnish" it's an essential must-have.

Salt! Thanks to my grandfather's health issues, I grew up in a low-salt house, so I was never a big fan of salty food. And I equated the use of salt with salty food. What a revelation when I discovered what an amazing addition it was to my cooking (in moderation, of course...)!

Tarragon! I recently made a stuffed mushroom recipe that called for it and the sorta-vanilla-sorta-licorice flavor blew up. I'm trying to work it into everything now and just started another pot in my herb garden to grow some fresh.

seasonality/locality(those are ingredients right?)...when you eat what's ripe and what was in the ground or on the tree near to the time you cook it...everything tastes better.

Using whole spices instead of ground really took my cooking to the next level. Whether its Indian food or anything else, using whole spices just makes the dish. Roast them and take them out later or roast them and grind them on the spot -- either way the flavors explode like pre-ground stuff never could.

Butter. I worship at the altar of Paula Deen.

coarse salt

Tomatos still on the vine. Growing up, we usually had the tasteless supermarket variety. Fresh tomatos in salads, salsas, or just by themselves makes such a huge difference.

Agree with the herbs comments, but if you don't have any fresh herbs in the house, keeping those frozen cubes (from Trader Joe's and probably other places) is a great backup. Cilantro, parsley, oregano are standards in my freezer, as are garlic and ginger. Pop them in sauces, guac, whatever, and you have good flavor without any shopping or chopping. Far and away better than using the (ugh) dried stuff. There are also tubes of usual and unusual ingredients to keep in the fridge, including lemongrass. I also use the cilantro and ginger flavors. Looooooooove cilantro.
PS: Put a little hoisin sauce in your leftover Chinese food to pep it up.

it's hard to say, so I'll just go with my most recent discovery- lemon and lime zest. I know others have said it, but with both savory and sweet dishes, that one addition can just make a food sing.

Bacon salt. Period. http://www.baconsalt.com/

Truffle oil! I first picked this up in Italy several years ago and it brought a pricey ingredient to a more affordable level. I quickly discovered that it could change even the most mundane item (scambled eggs, popcorn, etc.) to something sublime and special. And would take a nice dish and kick it up a notch, like risotto or flat bread pizza. I love my truffle oil.

Cheese! 10 years ago, the only cheese I would ingest would be melted on pizza. Now I've got a fridge drawer filled with no less than 15 different kinds. Making up for lost time, you know.

Thai basil - incredibly deep and intoxicating flavor
Szechuan peppercorns - fruity, nutty, numbing and absolutely unique
Chinese sesame paste - creamy and enveloping roasted sesame taste

Curry Leaves. My indian cooking was always missing SOMETHING and this is that something.

For more everyday cooking I would have to say Kosher salt as well. Nothing changes a dish like its salt content.

My cooking was greatly improved when I started using fresh herbs, and my favorite is basil. I LOVE freshly made pesto on chicken breasts, pasta, and smeared on a slice of fresh Italian bread...YUM!

salt. salt. salt.

Different varieties of garlic...there are so many out there, and each has its own unique flavor.

dill - it amazes me and i can't get enough

My cooking takes a dramatic turn during the summers when I receive a crop share box from a local farm. I cook with ingredients that I normally wouldn't buy. This years revelations: fennel, kohlrabi, and asian greens.

Butter. My yearning for flavor has finally trumped my fear of fat, and I am discovering the joys of butter as if for the first time. I cannot get enough!

Sugar.
Once I started using sugar my Asian inspired dishes tasted much more...Asian. Korean food is so much tastier! If possible I use honey, but sometimes the flavor overwhelmes. And of course a decent pasta sauce needs sugar too. Actually, my grandmother taught me that.

Crawfish and Tony Cacheres seasoning are my picks. I was introduced to them along with Cajun cooking by my Cajun in-laws and have been hooked since.

Local, fresh vegetables. We decided to start shopping locally at farmer's markets this summer - and it has really changed the way we eat. Even the simplest dishes (for example: Brandywine tomato sandwiches) taste complex and delicious.

There is no substitute for freshly grated nutmeg in my favorite baked goods and Indian foods.

Wine. Some for the dish and some for the cook!

Very carefully deployed fish sauce.

Fresh picked basil. I made Haalo's recipe for Basil Ice Cream recently, and it is delicious!
http://cookalmostanything.blogspot.com/2007/01/basil-ice-cream.html

thats easy - good salt.

As someone who grew out of being a picky eater in a meat-and-potatoes kind of household, anything that isn't American "comfort food" was revolutionary. Wine, capers, curry, olives, mushrooms, za'ater, and fresh herbs made a world of difference for me, as did learning to make my own dressings and sauces. I don't know if I could pick just one kitchen item that made more of an impression than another.

Sriracha!!

First press Greek olive oil, almost straight from the orchard!

Or a lemon.

Or the humble corn torilla.

Freshly cracked black pepper for desserts and sweet items. I cube cantaloupe, shred prosciutto and basil, squeeze some lemon on top and crack lots of fresh black pepper on top. I would analogize it to adding salt to baked goods. You wouldn't expect the synergy to work but it does.

Fresh Ginger grated into almost everything I cook recently!

Paneer. I have always loved eating Indian food at restaurants but recently ventured into a local Indian market and discovered you can buy paneer already made! Paneer is Indian cheese that is more like a really firm tofu and is pretty much a vegetarian staple for Indian food. It has really emboldened me...:)

Various vinegars; I grew up only being familiar with distilled white and apple cider. Now I have about eight different kinds. I love how adding a splash of vinegar at the end of cooking stews, beans, etc. just lifts the flavors and makes it all come together.

Pomegranate Juice has been my one of my most recent enthusiasms and it's now a staple in my refrigerator. It's great in sauces and marinades and, while it doesn't seem to insinuate it's particular taste to a dish, it adds a richness or a depth of flavor when used judiciously.

In addition, it's full of antioxidents, etc and serves as a substitute when one wants to add wine, but chooses not to because it's not desired for any number of reasons.

It's good and good for you.