Hi, I received an invitation from a restaurant to cook for an etnic night. I have no idea how to charge.
Any ideas?

How much do you think?????
How hard will you work???
Will you be doing the prep??
How many hours?????

How much do you think????? HAVE NO IDEA
How hard will you work??? I WILL WORK ON A MENU WITH 3 ENTREES, 3 APPETIZERS, 3 DESSERTS, FOR ABOUT 30 PEOPLE
Will you be doing the prep?? YES, MAYBE I CAN HAVE ONE PERSON HELPING
How many hours????? AT LEAST 6
I STILL HAVE NOT DISCUSSED IF I HAVE TO BRING INGEDIENTS OR IF IT IS UP TO THEM
IF IT WORKS, I WILL PROBABLY DO IT ON A REGULAR BASIS EVERY WEEK OR EVERY MONTH

It depends on how much you value your time and work. There are many answers but, only one that's right for you and only you can figure that out!
Personally I won't work for less then $40.00 an hour and consulting for no less then $150.00 but not everyone has the same expectations.