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Oroshigane, traditional Japanese graters, come in all shapes and sizes. From orosu (to grate or cut) and kane (metal or metal tool), this kitchen essential was originally made exclusively of copper or steel. Now stainless steel, aluminum and plastic predominate, but one can still find graters made of copper (or tinned copper) as well as ceramic, bamboo and even wood. A small, specialty grater made of sharkskin stretched over a wooden paddle is used in top-end restaurants and by sushi chefs to finely grate fresh wasabi root.

Koimo oroshi kake is a simple dish, enjoyed any time of the year.
Rick LaPointe photos

The most commonly grated items in Japan are vegetables — daikon, ginger root, carrots — that are used as garnishes (yakumi) in sauces such as tempura dipping sauce. Some starchy potatoes — yamaimo or nagaimo — are grated raw to a rather slimy (I should refrain from calling it snotty, but that is the best word) consistency and served alone with soy sauce (tororo imo) or as a garnish for cold soba noodles. Finally the oroshigane is occasionally used to grate some proteins, semifrozen fish for example, to make them easier to pass through a sieve. As for Western applications, there are many — I use an oroshigane to make quick work of very dry, aged Parmesan cheese.

However you use it, the oroshigane — found in thousands, if not millions, of Japanese homes and restaurants — passes all of the tests for a handy, durable kitchen tool that you will find new uses for each time you pull it out of the drawer.

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Koimo oroshi kake

I first encountered this simple dish at a restored traditional farmhouse in the hills of Hyogo Prefecture. It was served as the simmered course (taki-awase) in an o-sechi (New Year food) presentation. Little satoimo were gently simmered before being quickly fried and then doused in grated daikon and a savory broth.

A chef shows how to grate daikon and then strain out the excess liquid.

The Japanese word imo covers a range of tubers and rhizomes that include potatoes (jagaimo), yams (yamaimo), sweet potatoes (satsumaimo) and taro (satoimo). Taro is a small hairy tuber cultivated and eaten extensively in West Africa, the Caribbean, Central and South America and Polynesia. In Japan, taro, known also by the name koimo (small potato), is generally peeled, parcooked by boiling and then slowly simmered in seasoned dashi until the consistency is creamy soft while still maintaining its potato shape. Some people’s skin reacts to uncooked taro — it is slightly toxic raw and should only be eaten after thorough cooking. Those who are allergic should wear latex gloves or wash their hands immediately after handling.

Daikon, the flavor that determines this dish, can be seen in some form in practically every Japanese meal — perhaps sliced or grated raw, pickled whole or even simmered in large cross sections. Here, daikon is grated on the rough side of the oroshigane and squeezed of excess juice before being flavored by a 4:1:1 koikuchi stock — four parts katsuo dashi, one part mirin and one part dark soy sauce (koikuchi shoyu). Summer daikon is sharper than really good midwinter daikon and must be wrung out more firmly.

Accented with grated ginger and hari-nori (fine, needlelike cut laver seaweed) year-round or with something more seasonal — e.g., freshly forged myoga (Japanese ginger) in the late summer — and served with a bowl of hot rice and some pickles, koimo oroshi is sure to please everyone.

16 medium-size taro (about the size of ping-pong balls) 4 cups grated daikon 1 or 2 myoga, thinly sliced buds

Simmering broth

4 cups dashi (or any light stock)
2 teaspoons usukuchi shoyu
1 teaspoon salt
2 teaspoons sugar

Daikon oroshi broth

1 cup dashi
1/4 cup mirin
1/4 cup koikuchi shoyu

1) Place raw taro roots in stainless steel bowl with small amount of water and agitate — rubbing skins together to remove dirt and hairs.

2) With a small sharp knife, peel each and place in pot of cold water to prevent starches from changing color.

3) In pot that will hold three times more water than the volume of taro, bring taro to a boil and reduce heat to simmer 5-10 minutes, until a toothpick may be inserted to center but while taro is still fairly firm.

4) Remove pot from heat and run under cold water until taro roots are cool. Strain and return to pot.

5) Simmer for five minutes in 4 cups of dashi, add usukuchi shoyu, salt and sugar and continue simmering five more minutes.

6) Remove from heat and place in ice bath (large bowl with ice water will do fine) to cool; this is important, taro will suck up the flavored dashi while cooling. You may proceed this far one or two days in advance and refrigerate taro in the dashi until use.

7) On rough side of oroshigane, or fine side of Western box grater, grate daikon, squeeze excess liquid out with bamboo rolling mat (makisu) or damp kitchen towel and set aside.

8) Drain taro and pat dry with paper towel, dust with cornstarch or potato starch (katakuri-ko) and deep fry (180 degrees) in enough oil to cover until skin is golden brown and begins to crisp.

9) While frying taro, combine daikon oroshi broth in small pot and bring to boil. Remove from heat and, while still hot, add the grated daikon.

10) Remove taro to four serving bowls and ladle over hot oroshi broth.

11) Garnish with myoga and serve immediately. Serves four.

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