Place konbu in instant pot with 12 cups water. Turn on sauté. Bring to a boil. Push "keep warm" and let steep for 10 minutes. Remove konbu from broth and save for another purpose or discard.
While konbu is simmering, place pork hock in a large stock pot. Cover with water. Place over high heat. Bring to a boil, then rapid boil for 15 minutes. Remove hock from water and save, discarding water.
Add boiled pork hock to konbu-flavored stock in instant pot. Close lid and pressure cook on high for 60 minutes. Allow natural pressure release. Discard pork hock, saving broth.
Add chicken, bacon, shiitakes, and vegetables to broth in instant pot. Close lid and pressure cook on high for 75 minutes. Allow natural pressure release. Remove from broth. Chicken meat and shiitakes may be saved for another use.
Strain broth through fine mesh strainer. Return to instant pot, or at this point broth may be refrigerated or frozen for later use.
Just prior to serving, season broth with tare. Mix soy sauce and mirin together. Add to broth. Taste. If it isn't strongly flavored, add a pinch or two of salt, more soy sauce, or a few dashes of fish sauce. Taste again. Continue to adjust until desired level of saltiness reached.
Pour steaming hot broth over your favorite noodles and ramen toppings. Enjoy!