While I'm a huge Star Wars fan, I have to question the efficacy of lightsabers being used to eat food. According to Wookieepedia (yep-there's a purely Star Wars Wiki out there), lightsabers are "... a blade of pure plasma energy emitted from the hilt and suspended in a force containment field. The field contained the immense heat of the plasma, protecting the wielder, and allowed the blade to keep its shape."
These guys demonstrate the effects of a lightsaber quite well:
Ouch. I think that makes it easy to see a that a lightsaber being used to cut food-or even to cook food-would be dangerous, but feasible. But to eat with one (much less two) would be foolhardy to say the least.
It appears that Kotobukiya, manufacturer of a wide-range of Science Fiction and Fantasy based toys, has come up with a solution that may poke out an eye, but won't hack off a body part:
Luke Skywalker
Mace Windu
Darth Maul
These light saber chopsticks from a galaxy far, far away are nine inches long and come with little display stands. The Darth Maul sticks attach together (like in the film) to form one, dual edged weapon-though I'm not sure how practical it would be to eat with this:

This is probably what a lightsaber duel would look like on the Food Network.
No limbs lost. I'm a bit disturbed that I find this fact somewhat depressing...
Kotobukiya plans on coming out with a series of accessories (plates and soy sauce dishes) thematically designed to be right out of the Star Wars universe. I intend to buy a couple of sets of these, as well as the chopsticks.
However, a little part of me wishes that they looked like this:
Head on over to Amazon or the Star Wars Shop to eat your sushi with a more "elegant weapon for a more civilized day." (See light saber chopsticks)