What is tonkotsu?

Tonkotsu (豚骨) means pork bones in Japanese. Japanese cooks use the word for the broth made from these bones and for the ramen style that goes with it. The broth comes from Kyushu, the southernmost of the four main Japanese islands. Kurume is considered the place of origin, and the ramen stalls of Fukuoka made it famous. There you eat Hakata ramen with thin, straight noodles that cook for only one minute.

Why the broth turns white

For tonkotsu you boil the bones over full heat. The rolling boil releases collagen from skin and bones and whips the rendered fat into fine droplets. The gelatin keeps these droplets suspended, and the broth turns white and creamy without milk or cream. If you simmer the same bones gently, you get a clear broth, called chintan in Japan. The cloudy version is called paitan.

The right bones

• Pork trotters: They give plenty of collagen and make the broth silky. You get them from the butcher or frozen at an Asian grocery store.
• Marrow bones and backbone: Have the butcher saw them open. Open bones release more marrow, which adds flavor and color.

For 2 kg of bones, use about half trotters and half marrow or back bones. For 4 to 6 bowls you need about 2 liters of broth at the end.

How to make the tonkotsu broth

Blanching

Boil the bones hard for 10 minutes, pour off the water and scrub them under cold water. Remove dark blood and residue at the joints with a brush. If you skip this step, the broth turns gray and smells harsh.

Boiling and topping up

Start the bones in fresh water and skim off the foam during the first half hour. Then keep boiling over high heat and top up with hot water every hour so the bones stay covered. If the pot boils down too far, collagen scorches on the bottom, and you cannot get that taste out again. After 8 hours the broth is cloudy, after 12 hours it is creamy. Expect your kitchen to smell of pork for hours, and open the window.

Season in the bowl

The broth stays unsalted. Into each warmed bowl, put 1 to 2 tbsp tare and pour 350 to 400 ml hot broth over it. With shio tare you taste the pork flavor most clearly, and shoyu tare makes the soup darker and more savory. The principle is explained in the article on ramen tare.

Common mistakes

• Too little heat: The broth stays clear and thin.
• Noodles cooked in the broth: The starch makes the soup gummy. Cook the noodles in a separate pot with plenty of water.
• Broth salted in advance: With the tare, the bowl then tastes too salty.
• Cold bowls: The broth cools and the fat settles on top. Rinse the bowls with hot water first.

Toppings for tonkotsu ramen

The bowl gets slices of chashu, half a ramen egg, scallions and bamboo shoots. In Fukuoka you sprinkle red pickled ginger (beni shoga) and sesame over it, and wood ear mushrooms (kikurage) are often added. In Kumamoto, mayu goes on the soup, a black oil made from roasted garlic. You find a sequence with all the components in the recipe for tonkotsu ramen with chashu.