Cut beef sinew and place in a pot with 2 cups of water(this is extra water, not listed in the ingredients).
Bring it to boil over high heat, then turn the heat down to low for simmering it for 2 hours.
Skim off the scum and fat sometime.
After 2 hours simmering, drain the water and set aside the meat.
Prepare Daikon radish
Wash and peel the daikon.
Cut daikon about 2cm(0.8inch) thick and round off the edge.
Place them in a pot with enough water to just cover the daikon radish.
Cook it over medium heat for 30 minutes.
Cut konnyaku piece in half diagonally to create triangle shape.
Boil water in a pot and add cut konnyaku piece.
Cook konnyaku in boiling water for 5 minutes. You can turn down the heat to medium while the konnyaku being cooked.
Drain the cooking water and set konnyaku aside.
Place oden soup mix in the pot(clay pot or ordinary pot) and add 2 cups of water.
Place the pot over medium heat. Dissolve the soup mix and bring it to simmer.
Add all oden ingredients that you prepared (beef sinew, daikon, konnyaku, fish cakes, etc).
Simmer them for at least 1 hour for macerating the taste.
Before serve, mix mustard powder with water in a small serving plate.
Serve oden hot with mustard.
*1 if you can not access and making the soup from scratch, follow this recipe for the stewing soup. Dashi stock 4 cups, Sake 3tbs, Mirin 1.5tbs, Sugar 1/2 tbs, Salt 1/4 tsp, and Soy sauce 1tbs into a pot altogether and bring to simmer. *2 I have a small family so I bought a mixed fish cakes pack for Oden. You can buy those separately from Japanese grocery stores.