Can prospective hires "stage" in my restaurant?

The short answer is, "probably not."

While the law does permit a "working interview" it also requires that the applicant be fully onboarded as an employee and that the employer pay withholding taxes on the wages earned during the "interview."

The exceptions to this are:

Where the applicant simply observes the work environment, without actually performing any work; and
Where the applicant completes a skills assessment test during a normal interview. This can be a hands-on test if you're trying to assess someone's kitchen skills.