Step 1

In a large pot, soak kombu in the water for at least 30 minutes, up to 3 hours. Then bring to a lively simmer over medium low heat. This will take about 20-30 minutes.

Step 2

Before the dashi begins boiling, take the kombu out (boiled kombu will cause your dashi to become bitter and slimy) and strain dashi into a large bowl lined with cheesecloth.

Step 3

Bring all the ingredients to simmer in a saucepan.

Step 4

Simmer the tare until it reduces to ½ cup, about 25 minutes.

Step 5

Strain the solids and let the tare cool. Store in an airtight container in the refrigerator for up to two weeks.

Step 6

Place the chicken backs and pork bones in a heavy bottomed stock pot. Add enough water to fully cover them. Cover with a lid. Over high heat, bring the water to a boil. Once boiled, drain the bones and wash any dark marrow or coagulated blood off from the pork with cold water and a chopstick or fork. The bones should have no dark color left in them to obtain a light, milky color.

Step 7

Rinse the pot, put the bones back in along with the rest of the ingredients for the broth except the fatback. Add water to just cover the ingredients. Over high heat, bring the water to a rolling boil, then turn down temperature to a low boil/very lively simmer. Let boil for 12-18 hours, adding water to keep the ingredients submerged.

Step 8

The last 30 minutes to 1 hour before it’s done, place the fatback on a sieve or strainer, shallowly put it into the broth, cover the pot and let the fat cook. Remove and finely mince the fat. Keep in an airtight container in the fridge until ready to serve.

Step 9

Pour the broth through a fine mesh sieve into a large bowl (or multiple containers) to remove solids. Let chill in the fridge until solid, then spoon the fat off the top.

Step 10

Lay pork belly on cutting board and roll up lengthwise, with skin facing out.

Step 11

Using butcher’s twine, tightly secure pork belly at 3/4-inch intervals.

Step 12

Preheat oven to 275°F. Heat water, garlic, ginger, sliced green onions, soy sauce, mirin, fish sauce, white sugar in a medium saucepan, big enough to hold the pork belly, over high heat until boiling. Add pork belly, it won't be submerged. Cover with a lid left slightly ajar. Transfer to oven and cook, turning pork occasionally, until pork is fully tender and a cake tester or thin knife inserted into its center meets little resistance, 3 to 4 hours. Transfer contents to a sealed container and refrigerate until completely cool.

Step 13

Reheat pork belly slices in soup broth with noodles and other garnishes.

Step 14

In a large pot, bring the tonkotsu broth to a simmer. Add 5-6 cups of dashi. Finely chop the fatback and add the fatback to the broth, simmering until it’s barely visible in the broth. Ladle the broth into deep, wide bowls, adding about 2-3 tablespoons of tare, leaving room for the noodles and toppings. (Freeze any leftover broth to use later.) Cook the noodles according to the package instructions and divide among bowls. Top each with 2 slices of pork belly, one soft boiled egg sliced in half, 3 slices of naruto, 1 sheet of nori, the enoki mushrooms, oils, and scallions.

Step 15

Serve immediately.