Tsukemono plays an important role in Japanese cuisine: adding a big kick of flavor (with no fat and few calories) to otherwise mild-tasting food. Traditional Japanese cooking focuses on fresh, seasonal ingredients that are typically seasoned minimally to let each food's pure flavors shine through. This makes for mild and subtle dishes that shine with a Zen-like simplicity. Aside from the pungent kick of wasabi, which is typically eaten only with sushi, Japanese cooking does not employ the zing and spice of other cuisines, such as Korean. But that's where the under-appreciated pickle comes in.
Tsukemono refers to a broad category of pickles, many of which can be bought at an Asian market or made at home. Serve them in small portions (like those above) on the side of any meal, and try the parings I've suggested below. These are a few that I regularly buy. You can find them in the refrigerated section of most Asian markets that carry Japanese foods. In the picture, clockwise from top left:
1. Beni shoga (aka pickled ginger): This bright-red pickled ginger root is quite different from gari, the sweet, pale-pink slices of pickled ginger that accompany sushi. Colored with red perilla leaves (called shiso), beni shoga has a strong, salty, almost spicy flavor that adds a wonderful kick of flavor to dishes such as beef noodle bowls, stir fries, and yakisoba (stir-fried noodles). Ginger is widely purported to help quell nausea, so when I'm feeling under the weather, I often eat this type with ochazuke (o-CHA-zu-kay), which is simply green tea poured over rice (kind of like milk on cereal). Look for it in plastic tubs about the size of a tuna can.
2.Takuan (pickled daikon): Though the version above is dyed yellow, this pickle sometims looks paper-white or beige. Made from daikon, a mild white radish that can grow to the size of your forearm, it has many uses besides pickles: grated in dipping sauces, shredded into a mound of ribbons that go well with sashimi, and boiled in soups, to name a few. Takuan has a pleasant crunch and mild brininess, and it is eaten at the end of a meal, as it is believed to aid in digestion. You can buy it sliced, or as a whole radish immersed in a bag of brine.
3. Rakkyo (RAH-kyoh; aka pickled shallot): Similar in appearance to a cocktail onion, these crisp, mild, sweet-and-sour shallots, pickled in a light seasoned vinegar, are like candy to me. Often served with grilled fish or meats, they provide a crisp, bright note that's palate-cleansing between savory bites. Rakkyo is often labeled "pickled scallions" and sold in little plastic bags or small glass jars.
4. Umeboshi (ooh-meh-BOH-she; pickled Japanese plum): This is the quintessential Japanese pickle. One of my favorites, umeboshi is colored red with shiso and has a startling tartness that almost makes your eyes water (in a good way). It's an acquired taste for some. They are sometimes pale pink, and sometimes bright red, and they range from cranberry-sized, crunchy fruits to olive-sized fruits with a squishier texture. They are served with many meals, including breakfast, and are often placed in the center of onigiri (seasoned rice balls). Look for them in small plastic containers.
Make your own: I have never tried this, but from what I understand, some types of tsukemono are relatively quick and easy to make (while others aren't worth the effort). The quick-and-easy variety have a limited shelf life, while the ones that require more time to ripen tend to last a bit longer in the fridge. Check out Just Hungry's tsukemono post for more detailed descriptions, and make sure to see her quick-tsukemono pickle recipes. (I know I keep linking to this blog, but it's the best resource I've found on authentic Japanese food. If you know of others, please share!)
* High sodium content is the primary pitfall associated with Japanese food. For this reason, many of these pickles are best eaten in small quantities. Cooking Light usually recommends using reduced-sodium soy sauce as another way to keep sodium levels in check.