What a good question. As a preschool teacher myself, I would want to know why your child wasn't eating lunch. If you told me what was behind it, here's what I would do:
I would use some books and literature which explains 'difference' in ways youngsters can understand. I would bring Rosemary Wells book, "Yoko", in which the title character brings her favorite food, sushi, to school and is confronted by children who make negative comments.
I would also invite you to make enough of your daughter's favorite dish and then to serve it at a snacktime. I'd also invite other families to bring a snack-sized portion of a healthy dish their family enjoys to share at snacktime too.
I would (and have) use Katie Kissinger's book "All the Colors We Are" which discusses the reason we look different: our parents, our ancestors, and the parts of the world our ancestors came from. One of the activities we do is to use tons of paint swatches to find our best match for each child's eye color, skin color, lip color, hair color... I let the child help find the best matches with a mirror, then we tape/glue the paint swatch onto a piece of paper and write the name of the swatch color--or a child's choice of name for the color-- onto the paper. Thus, children learn that we are *all* different shades of brown and that every color we are is lovely.
Lastly, I would give your child plenty of empathy and focus on the fact that some kids simply don't understand how wide and wonderful the world is. But do have her go back to school. Find commonalities as much as you can, when it's appropriate. We adults can understand that there is a human instinct to categorize/sort people and things by type, but kids can't appreciate that. Do let your child know that you like that she has a wide range of friends, and that she has something special in her life by having a culture that is rich in tradition, even if it isn't reflected back to her. Let her know, too, that only she can decide not to eat her favorite foods-- just because her daycare friends find sandwiches to be their favorite foods doesn't mean that she should stop eating *her* favorite food.
(and as a teacher, I would likely take the teasing child/ren aside and run a little 'empathy check'... "I noticed that you were teasing Suzy about her lunch today. Can you tell me about that? How do you think Suzy feels when you make that say that to her? Do you think that makes her feel happy or sad?" etc.
I hope this helps a little. I'm sorry you and your daughter are having to experience this. I am Caucasian but my adoptive father is Filipino... when I moved to the mainland from Honolulu, I was the only kid I knew who ate Kim Chi, lumpia and other delicious foods. I can relate-- it really, unfortunately, is a lack of exposure to other cultures.