Nanakusa-gayu (ななくさがゆ, or 七草粥) is the porridge (Congee) that you eat on January 7th, 2011 [ Wikipedia ]. Take a rest from eating all kinds of festivity food in Japan during New Year's (おしょうがつ).
This is the nanakusa-gayu that Katz ate earlier today.
It's not tasty at all but very thin. Many Japanese restaurant offer the special Nanakusa-Gayu menu this weekend.
"Nanakusa" means "seven (7) vegetables". So this porridge has 7 different kinds of vegetables in it.