It's/these are delicious!

[Winwin2011]

A: These are delicious! What are they?
B. Oh, that's cauliflower.

Is it corect to say 'Oh , those are cauliflower'?'

Am I right if the context is changed as follows ?

A: It's delicious! What is it?
B. Oh, that's cauliflower.

Thank you.

[emsr2d2]

A: These are delicious! What are they?
B. Oh, that's cauliflower.

Is it corect to say 'Oh , those are cauliflower'?'

Am I right if the context is changed as follows ?

A: It's delicious! What is it?
B. Oh, that's cauliflower.

Thank you.

"It's cauliflower, and it's delicious" is fine. You would only use the plural if you said "Those are cauliflower florets" - perhaps in answer to someone who specifically pointed at those pieces of food on a plate and said "What are they?"