Pressure Cooker Tonkotsu Ramen with Rich Pork Broth

Method

1. Rinse the pork leg bones and hock under cold running water. Soak them in a large bowl of water for 15 minutes, changing the water a few times, to draw out blood. If using backbones, remove any white spinal cord tissue with chopsticks to avoid a strong odor.
2. Meanwhile, peel the papery outer layers from the garlic head, keeping it whole. Trim the root end and slice the head in half crosswise. Slice the ginger into thin rounds, skin on.
3. Place the bones, hock, ginger, garlic, and 2 QT water in a pressure cooker pot or Instant Pot inner pot. Ensure the water doesn't exceed the max line. Lock the lid, set the valve to Sealing, and cook on high pressure for 60 minutes. (If you don't have a pressure cooker, use a large stock pot with 2 cups extra water and simmer uncovered for 3–4 hours, partially covered.)
4. While the broth cooks, make the cold-brew dashi: combine 2 cups water, kombu, dried shiitake, and iriko in a bowl. Let it sit at room temperature to extract umami.
5. For the shoyu tare, combine sake, mirin, soy sauce, and water in a small pot. Add the small kombu piece and heat over medium until nearly boiling, then simmer on low for 3–4 minutes. Turn off heat, stir in the salt until dissolved, and let cool. Do not reheat after adding salt.
6. Prepare the hidden seasonings: cut the onion in half with skin on, and cut the scallions in half crosswise. Set aside.
7. When the pressure cooking finishes, quick-release the steam carefully. Open the lid, then bring the broth to a hard boil (using Sauté mode on Instant Pot or high heat on stove). Skim off scum with a fine-mesh skimmer, being careful not to remove too much fat.
8. Add the onion, scallions, rice vinegar, sake, and the shiitake and anchovies from the dashi (reserve the dashi liquid). Add the katsuobushi and stir well.
9. Keep the broth at a rolling boil for 30 minutes, stirring from the bottom every 10 minutes to prevent scorching. After 30 minutes, pour in the reserved dashi liquid (discard the kombu). Continue boiling for another 30 minutes, stirring occasionally, to emulsify the broth.
10. After a total of 1 hour of boiling, turn off the heat. Remove the large bones with tongs and place them in a strainer set over a pot to drain, then discard. Remove other solids and press them in the strainer to extract all liquid.
11. Strain the broth in batches through the strainer, pressing the solids well. Your tonkotsu broth is ready. If storing, cool it quickly in an ice bath, then refrigerate for up to 3 days or freeze for 1 month.
12. To serve, bring a large pot of water to a boil and heat the broth. Warm your ramen bowls with hot water, then discard the water and add 1 tablespoon of tare to each bowl. Cook the noodles according to package instructions, then drain and divide among bowls. Pour about 1½ cups of hot broth into each bowl, add your toppings, and serve immediately.