<<Disclaimer: Verify this information before applying it to your situation.>>

I visited my local Taco Bell today and asked for a list of ingredients in
the tostada shell. The store manager brought the box they are packaged in
for me to examine for myself. The list printed on the carton is exactly as
Joseph Zaccardi reported. This is consistent with my personal experience of
eating Taco Bell Tostadas (no cheese) without reaction since 1975.