A Lavish meal is created at a Cook stove and requires 0.5 nutrition from animal products and 0.5 nutrition from vegetables to create. A colonist with cooking skill of at least 10 is required to create this meal. When eaten it causes the Ate lavish meal thought with a 10 mood bonus. Lavish meals restore 1.0 saturation.
It's rather wasteful when compared to other meals; with the same ingredients you can make 2 fine meals for a total of 1.8 nutrition. Thus you should save this for mid-late game where food won't be an issue most of the time.