There's a guy on Reddit named Ramen Lord who posts these epic multiple day ramen recipes. Here's just the broth
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Broth:
The ubiquitous tonkotsu broth requires three characteristics to turn white and creamy:
Low starch/sugar content in the boiling liquid.
High volumes of fat and gelatin.
Rapid agitation of the pot’s contents.
If any of these are off, you won’t get the tonkotsu you crave. Reasons below:
The sugars in aromatics (onion, carrot, apple) caramelize and turn brown. I had been chasing this idea that arromatics were required, but the truth is that most tonkotsu shops use an all-animal approach, opting to add aromatic compounds in things like tares and aroma oils later on.
Gelatin is a surfactant that emulsifies the fat from the bones, creating the characteristic opaque, white color. Getting the balance is key though; too much gelatin and your broth will be overly sticky and unappetizing. Not enough, and you won’t be able to emulsify the fat.
To get that emulsification, you have to churn the contents in some capacity, which decreases the size of the fat globules and allows them to emulsify. To do this, a rapid boil is required. Agitation also has the benefit of reducing the amount of water soluble proteins that rise to the surface, which can actually brown over time if they aren’t mixed back into the liquid.
Now… for the tricks.
No one said this needed to rapidly boil all of the time. The rapid boil acts quickly to emulsify things if the gelatin level is appropriate. Which means the cooking can start at a simmer, and build up later! So you can actually start this the night before, keep things at a safe, low temp during the night, and then crank it up to high heat the next day, with the same results.
Covering the pot increases the pressure in the vessel, which helps promote agitation, saves heat, and water. Do it.
You can use a combination of bones. Can’t find femurs? Try neck bones. This iteration uses half neck bones, half femurs.
The addition of fatback boosts the fat levels, creating the right balance of fat to gelatin.
Ingredients: (Makes maybe 8 qrts of stock total)
8 lbs total in bones (I used half femurs, half neck bones. All neck will work in a pinch)
About .8lbs fatback. (10% the weight of the bones).
Steps:
Before any cooking, soak the bones in cold water in a large, non-reactive vessel, for at least 6 hours, and up to 24 hours. (I use a large plastic container).
The night before you want your broth ready, drain the bones, add them to a pot with fresh water covering them by 2 inches, and bring to a boil over high heat.
Drop the heat to medium, and blanch the bones, at a simmer, for 15-30 minutes, or until little to no scum rises.
Strain the bones again, and scrub away any black material, such as coagulated blood, from the bones and pot.
Return the bones to the pot. Add fresh water, and add in the fatback. If doing the night before, bring this to a boil, then down to the lowest setting on your stove, and cover. Then go to bed. If not, continue to step 7.
In the morning, bring the pot back up to a full boil, then back down to the lowest setting possible to mantain that jostling boil while covered. (For me, this is medium on my stove)
Depending on when you started cooking, continue to boil the broth for 12-18 hours, or until desired consistency and color is reached, meat has completely separated and broken down in the broth, and fatback pieces have mostly melted. Optionally, you can stir every 1-2 hours just to check up on things and promote more churning. Please feel free to add back water if the level gets too low.
Once cooked to your liking, strain the broth, discarding the solids, and reserve broth until needed over low heat. This broth keeps for around a week in the fridge.