Place the beef shanks in a large pot, cover with water, and bring to a boil. Boil for about 10 minutes.
1 kg beef shanks, water
Skim off the scum and any fat that rises to the surface. Remove the meat, then discard the blanching water.
Prepare the vegetables
Peel the onion and cut it into quarters.
1 white onion
Husk the corn if needed, then cut each ear into three pieces.
2 ears of corn
Cut the bok choy into bite-size pieces and chop the scallion. Set the vegetables aside.
1 bok choy, 1 stalk scallion
Cook the broth
Return the meat to the pot, add fresh water, and bring to a boil. Skim as needed until the broth looks clear.
Add the peppercorns, onion, and fish sauce. Reduce to a gentle simmer and cook for up to 3 hours, or until the meat is tender (pressure cooker: 45 minutes to 1 hour).
2 teaspoons whole peppercorns, 2.5 tablespoons fish sauce
Add the corn and boil for 15 to 20 minutes, or until tender. Season with salt to taste.
salt
Add the bok choy and cook for 2 to 3 minutes. Turn off the heat.
Serving
Serve very hot, with extra fish sauce and/or calamansi (or lime) on the side for squeezing in at the table. Add black pepper to taste.
black pepper, calamansi
Notes
Clear broth tip: blanching the meat, then discarding the first cooking water, helps produce a cleaner, less greasy broth.Cooking time: on the stovetop, simmer for up to 3 hours; in a pressure cooker, cook for 45 minutes to 1 hour, then finish uncovered to cook the corn and vegetables.Serving: adjust the salt at the end (fish sauce is already salty), and add the calamansi/lime right before eating.