Robby zhu posted:
This is the spice to season the rice with.
This is what to season the rice with.
Do you think the above two sentences are the same? （I'm not sure if even the second one is grammatical.）
Hello, Robby zhu,
No, those two sentences are not the same. The first one is about a spice; the second one need not be about a spice. The first one has an infinitival relative clause; the second one has a nonfinite embedded question.
The second example doesn't work very well, though it is not ungrammatical. It could work as a reply to the statement "I don't know what to season the rice with." Normally, however, English speakers would use "Here's", not "This is":
A: I don't know what to season the rice with.
B: Here's what to season the rice with.