Intensely popular, this is made with a porky, opaque pale broth with a sticky-lipped intensity and the rich, buttery texture of light cream, there's no smell more warming on a cold day than a big hot bowl of tonkotsu ramen set before you. The best sports tiny nubs of fat swimming around on their surface, a slick of mayu (black garlic oil) or chile-sesame paste, a handful of thin-sliced green onions, a soft-yolked soy-sauce tinged egg, and a few slices of meltingly tender chashu pork belly. It's the ultimate meal-in-a-bowl and what any Japanese businessperson—and a good deal of Americans these days—thinks of the moment you mention comfort food.
To achieve this, you boil your bones and aromatics as gently as possible—a bare simmer, with the surface barely quivering—meticulously straining the entire time to remove any impurities that might cloud your soup.
When making a Western-style stock, heating bones in water is a means of removing water-soluble proteins from the interior and exterior of the bones and dissolving them into solution, adding flavor to the water. The heating and simmering process also catalyzes a few other reactions, mainly the conversion of collagen—the protein that comprises most of the connective tissue—into gelatin, the familiar protein that thickens and adds richness to broth.
With tonkotsu broth, on the other hand, you go one step further. In this case, bones are cooked at a rolling boil for a long, long, long, long period of time. Not only does all the same dissolving and gelatin creation take place, but you also end up breaking down other matter—fat, marrow, calcium, various other minerals and proteins—into tiny tiny pieces which get suspended in the liquid, turning it opaque.
So how long does this process take? Up to 12 hours at a low boil on a stove-top.
Ingredients:
3 pounds pig trotters, split lengthwise or cut crosswise into 1-inch disks (ask your butcher to do this for you)
2 pounds chicken backs and carcasses, skin and excess fat removed
2 tablespoons vegetable oil
1 large onion, skin on, roughly chopped
12 garlic cloves
One 3-inch knob ginger, roughly chopped
2 whole leeks, washed and roughly chopped
2 dozen scallions, white parts only (reserve greens and light green parts for garnishing finished soup)
6 ounces whole mushrooms or mushroom scraps, such as cremini
1 pound slab pork fat back
For more umami taste, cooking the onions, garlic, and ginger until nearly black was the way to go. Also use mushrooms especially dried porcini.
Notes on the bones:
- Blanching the pork bones and rinsing them thoroughly of coagulated blood and other impurities ensures the final tonkotsu broth is a pale, rather than a deep, dark brown.
- Charring the aromatic vegetables adds complexity to the broth.
- Keeping the broth at a low, rolling boil ensures that the released fat and particulate matter emulsifies in the broth, which makes the broth opaque and creamy.
