Place a large stockpot over medium-high heat. Add sesame oil and onions, garlic, carrots and ginger.
Saute the veggies for 5 minutes, stirring constantly to avoid burning the garlic.
Pour in the broths and water; bring to a boil, then lower heat to a simmer and allow to cook for 1 hour...stirring occasionally.
Taste soup and add salt and pepper as desired.
To serve: strain veggies from broth and ladle into sipping bowls or tea cups. Add garnishes as desired.
This is a richer soup than served in local Japanese restaurants...give it a try! It freezes well, so do not hesitate to make this whole batch!