Simple Udon soup recipe in thermal pot

This is not necessarily something that needs a thermal pot, but the thermal pot was helpful in getting the flavours out of the vegetables without boiling for long periods of time.

Ingredients (serves about 10 bowls of udon)
2 litres of water200ml of kikoman or other japanese light soya sauce
4 table spoons of "Doshi" or the other term for it is "Bonito Bullion??" basically japanese fish flakes
4 table spoons of sugar
(the above in my mind are the basic ingredients, the rest below is up to you to alter the flavour)

I used stuff that is available and cheaply too here
1 stalk of leek - 79c new zealand - chopped fine
3 stalks of celery - less than a dollar - chopped fine
1 large onion chopped

Honestly no good way to say how to cook this except to dump all in the pot, simmer for about 15 to 20 minutes and then keep in thermal pot for about 3-4 hours.

In order to get a nice hot bowl of udon, I used instant udon (about $1 per packet).Boil the above soup in a pot, preferable just enough for 1 serving ( about 300ml per serving) then when boiling add in udon for between 1-3 minutes.

Transfer all contents into a bowl

Add on additional ingredients to flavour the udon eg - fish balls (sliced), strips of seaweed, japanese tofu skin or break an egg in the soup during last stages of boiling.

I will upload the picture soon