Interesting idea, Aunty Sue, but be careful. All assessments must be planned and the candidate must have prior knowledge of what is to be assessed and how.
My approach is to agree that we will have a professional discussion about a specific topic and encourage the candidate to think about his/her evidence beforehand, making notes to prompt them in the discussion.
It is true that candidates do find professional discussions difficult, especially at level 2, so I do find myself having to prompt the candidate.
Persevere, it will become easier.

Dave