Tonkotsu literally translates to “pork bone,” and the process for making this bone broth is completely different from any Western soup you’ve ever had. Instead of a gentle, barely-there simmer, tonkotsu is cooked by way of a rolling boil that lasts for hours. This method takes not only the collagen from the bones, but it also extracts the marrow, fat and minerals in a way that emulsifies everything into a rich, milky-looking broth that’s a favorite in ramen shops!
Tonkotsu ramen got its start in the Fukuoka Prefecture in Japan, just southwest of Honshu (the main island). The original form was developed in 1937, at a shop called Nankin Senryo. This shop started using a relatively clear pork broth (as opposed to the more common chicken broth) simply due to cutting costs, but the flavor caught on with the locals. It took another 10 years for modern tonkotsu broth to take form, when the owner of Sankyu accidentally left his soup on the heat overnight. It ended up being a happy accident, and Sankyu was able to open up several other shops around the prefecture because of the soup’s popularity.
When it comes to shopping for ingredients, pork trotters are a must. You probably won’t find them at your local Kroger, but they’re easy to find at Asian markets and specialty meat markets. These particular bones have higher levels of collagen than bones from other areas of the pig, which is crucial for the lip-smacking consistency of the broth. You can supplement with rib or neck bones, but make sure the trotters make up the main portion of the bones you use.
(The first time I made this, I think the ingredients startled my mom. After looking at the package of pork trotters on the bottom shelf of the fridge, she looked wide-eyed at me and said, “All right, you’re more Asian than me.” If you grew up in the US, it’s not exactly the first cut of meat you’d expect to see. 🙃)
Another unique part of this broth is the fact that you need to blanch the bones before you start the main cooking process. The raw bones still have some hemoglobin stored inside, and that protein can easily turn your light-colored broth to a deep brown. It’s an extra step in a long process, but boiling them for a few minutes and carefully rinsing them will ensure that your soup has the creamy color you want from tonkotsu.
This broth requires you to maintain a rolling boil for hours (most would suggest at least 12 hours, to get maximum flavor from the bones), so you will have to be around to keep an eye on the water levels. It’s a labor of love, but if you’re a noodle fanatic, this will be a fantastic treat to bring the ramen shop to your house!
8 oz button mushrooms, sliced
4 small shallots, peeled and halved
1 2-inch piece ginger, peeled
1 TBSP oil
6 lbs pork trotters
6 stalks green onions
3 sheets kombu
Salt and white pepper to taste
Preheat the oven to 400F. Toss the mushrooms, shallots, and ginger with the oil, and arrange in a flat layer on a parchment paper-lined sheet pan. Roast for about 20 minutes, until deeply browned.
Place the pork trotters in a large stockpot, and fill the pot with enough water to completely cover the trotters. Cover and bring to a boil over high heat. Boil for five minutes, then drain out the water and rinse the bones. Put the bones back in the pot, then add the mushrooms, shallots, ginger, green onions, and enough water to cover everything, then return to medium-high heat and cover. Boil covered for 12 hours, replenishing the water as needed. (You can shorten the time to as little as 6 hours, but the flavor will not be as rich.)
Soak the kombu in 8 cups of water for up to 3 hours. During the last 2 hours of cooking, use the kombu water to replenish the water levels in the broth.
In the last hour of cooking, add salt and white pepper to your liking. When the cooking time is up, remove from the heat and let cool slightly. Use a slotted spoon to remove the bones and aromatics from the broth.
Serve immediately over noodles, with the garnishes of your choice.
Makes about 10 cups.