Begin by filling a large pot with water and bringing it to a vigorous boil. Add the beef tendons and brisket, allowing them to cook for about 5 minutes. This initial boil helps remove excess fat and impurities. Drain the pot completely, then rinse the meats under cold running water, scrubbing gently to remove any scum or residue. Do the same for the konjac, ensuring it is thoroughly cleaned before cooking.

Return the beef tendons to a clean pot and pour in about 4 cups of fresh water, along with a pinch of salt. Bring it to a boil once more, then reduce the heat to low. Let the tendons simmer gently for approximately 1½ hours, or until they begin to soften and develop a gelatinous texture.

After this slow simmer, add the beef brisket, carrots, konjac, dashi stock, soy sauce, miso, sugar, and mirin into the same pot. Stir well to combine all ingredients, ensuring the miso dissolves evenly into the broth. Bring the stew to a gentle boil again, then lower the heat to a steady simmer. Cover with a lid and allow it to cook for an additional 45 minutes, so the flavors meld and the meat becomes tender.

Once the beef is soft and the broth has deepened in color, remove the lid and increase the heat to high. Continue simmering for about 15 minutes, or until the sauce slightly thickens and coats the ingredients beautifully. Taste and adjust seasoning with a pinch of salt and pepper if needed.

Turn off the heat and let the stew rest briefly before serving. Ladle into bowls and garnish with freshly chopped spring onions. This comforting Beef Tendon Stew is best enjoyed warm, its rich broth and tender meat offering a perfect balance of umami, sweetness, and savory depth.