The dish was one of the Vulcan dishes programmed into the food synthesizers on the Enterprise. However Commander Spock thought that with the pre-programmed settings the M'lu was not particularly edible.
While hiding from Yarblis Geshkerroth, who had wrested control of Captain Kirk's body from him, Spock had access to food synthesizer that had been outfitted with manual controls. As a result he was able to synthesize what he considered to be the first edible M'lu he had eaten in over three years. (TOS novel: Ghost-Walker)