Not sterilized, but given long lasting birth control without consent, or without clear consent.
Here's an article from Israeli newspaper Haaretz:
"A government official has for the first time acknowledged the practice of injecting women of Ethiopian origin with the long-acting contraceptive Depo-Provera.
Health Ministry Director General Prof. Roni Gamzu has instructed the four health maintenance organizations to stop the practice as a matter of course.
The ministry and other state agencies had previously denied knowledge or responsibility for the practice, which was first reported five years ago."
For the rest of the article, http://www.haaretz.com/news/national/israel-admits...
As for why an Ethiopian won Miss Israel, maybe the judges wanted to make a statement that they did not support the racist ideal of beauty you see in a lot of beauty contests etc. . . . and maybe this scandal had something to do with their wanting to make that statement!