Japanese traditional food –SUSI(1)

SUSI is my favorite Japanese food.　And these days many people can enjoy SUSI overseas as well.　So, many foreigners, when they come to Japan, are very eager to eat genuine SUSI.
Even I have heard that SUSI booms in foreign countries　these days, I am not sure how popular is SUSI among foreigners,
However some foreigners confuse SUSI and SASIMISO, it's useful if you can explain basic points like the fact that SUSI always contains rice.