Mochi — Japan's pounded glutinous-rice cake

i. Origin & history

Glutinous rice came to Japan with rice cultivation from the Asian mainland, and pounded rice cakes have been made there since ancient times. By the Heian period (794–1185) mochi was a food of the imperial court and of religious ritual, offered to the gods at festivals and eaten for good fortune. Rice was sacred, and concentrating it into a dense, long-lasting cake made mochi an ideal offering and a symbol of strength and longevity.

Its most important role is still at New Year. Mochitsuki, the communal pounding of mochi, traditionally takes place in the last days of December: steamed rice is placed in a large wooden or stone mortar (usu) and pounded with heavy wooden mallets (kine), while a second person quickly turns and wets the dough between blows. It is hard, rhythmic and social work, and is still done by families, neighbourhoods, temples and Japanese-American communities, though electric mochi machines have replaced it in many homes.

The New Year mochi has several forms. Kagami mochi, two stacked rounds topped with a bitter orange, is set out as an offering and broken and eaten in mid-January. Ozōni, a soup with mochi that varies by region and family, is eaten on New Year's morning. In other seasons mochi appears in sakura mochi for spring, kashiwa mochi for Children's Day, and countless regional sweets.

The word mochi is also used for the sweets made from it, which can cause confusion. Strictly, mochi is the plain rice cake; daifuku is mochi wrapped around a filling, ohagi is half-pounded rice, and dango are dumplings made from rice flour. Outside Japan, 'mochi' is often used for all of them.

ii. What makes mochi stretch

Mochi's stretch comes from its rice. Glutinous rice — mochigome in Japanese — has starch that is almost entirely amylopectin, a highly branched molecule, and very little of the straight-chain amylose found in everyday rice. When glutinous rice is steamed, the amylopectin swells and gelatinises; pounding then breaks down the grains and works the gel into a continuous, elastic mass that stretches, sticks and springs back.

Traditional pounded mochi has a slightly denser, more elastic texture than flour-based mochi, because the cooked grains retain more structure and less water. Shiratamako, a flour made by soaking, grinding and drying glutinous rice, gives the closest result at home; mochiko, a finer dry-milled flour, gives a softer, smoother texture that is excellent for sweets. Both need to be cooked fully with water until translucent.

Mochi hardens as it cools and ages because of retrogradation: the starch molecules gradually realign and squeeze out water, turning soft mochi firm and eventually rock-hard. Traditional New Year mochi is meant to harden, so it can be cut into blocks (kirimochi) and stored, then softened again by grilling, boiling or microwaving, which re-gelatinises the starch. Adding sugar to the dough, as most sweet mochi recipes do, slows hardening and keeps it soft for longer.

Grilled mochi is one of its pleasures. A block of hard mochi on a grill or under a hot grill crisps on the outside, then swells and puffs as steam forms inside, sometimes splitting open to reveal a molten, stretchy interior.

iii. Ingredients

Makes 8 servings · scroll the side panel to adjust

• 200 g shiratamako or mochiko (glutinous-rice flour)
• 40 g caster sugar
• 220 ml water
• 50 g potato starch (katakuriko) or cornflour, for dusting
• 30 g kinako (roasted soybean flour), to serve
• 2 tbsp sugar, mixed with the kinako
• 2 tbsp soy sauce, to serve
• 1 tbsp sugar or mirin, mixed with the soy sauce
• 2 sheets nori, cut into strips

The dough must be made with glutinous-rice flour — labelled shiratamako, mochiko, sweet rice flour or glutinous rice flour. Ordinary rice flour will not stretch. Sugar is optional for plain mochi but keeps it soft for longer; leave it out if you plan to serve the mochi savoury. Potato starch stops the dough sticking. The toppings make two classic ways of eating fresh mochi: kinako mochi, rolled in sweetened roasted soybean flour, and isobe mochi, dipped in sweetened soy sauce and wrapped in nori.

iv. Method

1. Whisk the glutinous-rice flour and sugar in a microwave-safe bowl, then whisk in the water gradually until completely smooth.
2. Cover loosely and microwave on full power (about 800 W) for 1 minute. Stir hard with a wet spatula.
3. Microwave for another 1 minute and stir again, then for 30–60 seconds more, until the dough is glossy and translucent throughout and stretches in long ropes. Alternatively, steam the bowl over boiling water for 20 minutes, stirring halfway.
4. Beat the hot dough vigorously with the wet spatula for 1–2 minutes, folding it over itself; this mimics pounding and makes it smoother and more elastic.
5. Tip onto a tray dusted with potato starch, dust the top and let it cool for 2–3 minutes. With starched hands, divide into 16 pieces and shape into small rounds or flat squares.
6. For kinako mochi, brush excess starch from half the pieces and roll them in the kinako mixed with sugar.
7. For isobe mochi, warm the soy sauce with the sugar or mirin until dissolved. Dip the remaining pieces in it and wrap each in a strip of nori. Serve at once.

v. Tips & common mistakes

• Cook until no white remains. Opaque patches are raw flour, which tastes chalky and will not stretch.
• Wet your tools, starch your hands. Water stops mochi sticking to spatulas; starch stops it sticking to you.
• Beat it while hot. A minute of vigorous folding gives a smoother, chewier texture closer to pounded mochi.
• Brush off excess starch. Too much leaves a dry, chalky coating.
• Eat in small bites. Mochi is very sticky and elastic, and every New Year in Japan there are warnings, especially for the elderly and young children, to cut it small and chew thoroughly.
• Do not refrigerate fresh mochi. It hardens fast in the cold; freeze instead.

vi. Variations

Yaki mochi is grilled block mochi, often brushed with soy sauce. Kusa mochi or yomogi mochi is coloured and flavoured with mugwort; mame mochi contains black soybeans; sakura mochi is pink and wrapped in a salted cherry leaf. In ozōni, mochi is simmered in broth for New Year, and in zenzai it floats in sweet red-bean soup. Filled mochi includes daifuku and red bean mochi, and modern forms include mochi ice cream and the baked mochi cheesecake.

Glutinous rice cakes are made throughout Asia: Korean tteok such as chapssal-tteok, Chinese nian gao for Lunar New Year, Filipino suman and Indonesian klepon.

vii. Serving & storage

Serve fresh mochi on the day it is made, with green tea. Kinako mochi is sweet and nutty; isobe mochi is salty-sweet and savoury. Both are traditional snacks, especially during the New Year holidays.

Fresh mochi stays soft for about a day at cool room temperature, wrapped. It hardens in the fridge. For storage, wrap pieces individually and freeze for up to 2 months; thaw at room temperature, or microwave for 10–20 seconds, or grill from frozen until puffed. Hard, shop-bought block mochi (kirimochi) keeps for months sealed and is softened by grilling, boiling or microwaving.

ix. More from Japanese

• Daifuku — mochi with bean filling
• Mochi Rice Balls — ohagi and botamochi
• Mitarashi Dango — glazed rice dumplings
• Zenzai — red-bean soup with mochi
• Nian Gao — Chinese New Year rice cake
• Mochi Ice Cream — ice cream in a mochi skin