Question

Have you ever seen a vegetarian tiger. (Start with Has a vegetarian tiger…?)​

Answer 1

Has a vegetarian tiger ever be seen by you?

or

Has a vegetarian tiger ever be seen?

This is the required passive voice.

We can omit "you" here as it's obvious the speaker is talking to the listener.

Notice that the stress has moved from "you" (Have you ever seen...) in the active voice to "a vegetarian tiger" (Has a vegetarian tiger ever...)

In passive voice, the stress is on the object, in active, it's the subject.