bitter tasting lettuce.

[urbanfarmer]

What is the best time of the day to harvest lettuce?

A. Research has shown that lettuce harvested at 7 a.m. contains up to 100% more sugar than leaves picked at 2 p.m.

The early bird gets the sugar fix.... :P
Do you think that applys to most veggie plants...?

I would think so. This happens in leaves; so, any plant where you eat the leaf will probably have a similar situation.