Separate the green onion into green and white parts. Slice the white part diagonally into 1cm pieces.

Place beef tendon in a pot with enough water to cover. Boil over medium heat for 1 minute, then drain and rinse the beef under running water.

Clean the pot and add beef tendon, green onion (green part), ginger, and enough water to cover. Bring to a boil over medium heat, then simmer with a lid on low-medium heat for 1.5–2 hours until the beef is tender.

In a separate pot, combine 700cc of the broth, beef tendon, and green onion (white part). Bring to a boil over medium heat, add seasonings, and stir until the curry roux dissolves (1–2 minutes).

Microwave frozen udon noodles in a heatproof container covered with plastic wrap according to package instructions.