Oil and other energy prices have come off the boil, again for reasons not yet clear (slowing economies and higher OPEC production?).

FORBES: Spelling Relief?

Add the sweet potatoes, cleaned leeks and plenty of ginger to the clear broth and bring it to an aggressive boil.

WSJ: Amaryll Schwertner's Poached Halibut in Dashi With Leeks, Sweet Potatoes and Sesame Seeds | Slow Food Fast