Bring a pot of water to the boil and add 500 g beef tendon (sinew). Boil for a few minutes to remove the excess fat and scum.
After a few minutes have passed, pour the sinew into a colander to drain and wash the beef sinew under clean running water.
Fill the pot again with approximately 1000 ml water (or enough to cover the beef by 1-2cm) and bring it to a boil.
While you wait for the water to heat up, cut the beef sinew into strips.
Once boiling, turn the heat down to simmer and add 1 Japanese leek (naganegi), 20 g ginger root and the beef sinew. Simmer for 1 hour without a lid. (Add more water when necessary to ensure the beef is always submerged.)
After one hour, remove the beef sinew and set it aside to cool. Discard the spring onion and ginger but save the broth. Continue to simmer the broth without a lid until reduced by one-third.
When the beef is cool to the touch, push the pieces onto skewers. (Approximately 100g per skewer)
Prepare the Daikon
Peel the skin of 300 g daikon radish and cut into thick rounds. Score one side with a cross, about 1cm deep.
Boil in a separate pot until it's easy to pierce (about 15 minutes).
Oden
Take a large pot and add 1 liter dashi stock and 100ml of the leftover broth from the beef sinew. Add 2 tbsp sake, ½ tbsp sugar, 3 tbsp mirin, 5 tbsp Japanese soy sauce (koikuchi shoyu) and 1 tbsp oyster sauce to the broth. Bring it to a boil and let it boil for 2-3 minutes.
Turn the heat down to simmer and add the daikon, 4 boiled egg and gyusuji skewers. (You should also add any other firm ingredients at this point.)
Simmer for about 30 minutes and then fishcakes of your choice, deep fried tofu (atsuage) and any other soft ingredients you choose. Simmer for another 15 minutes.
Serve up and enjoy with Japanese mustard (karashi).
Notes
Allow leftovers to cool and store in the refrigerator. Warm up on the stove before eating and consume within 2 days.
Note: While the nutritional information includes the full serving of broth, most people in Japan don't actually finish all the soup.