Define the behaviors that need to be assessed. Say X. Break it down to its components Y, which are actual behaviors leading to X. Ask questions like "Describe a situation" or "When faced with" (starting with any W or H, should be open-ended) and probe - you will have your answer.
Example:
Customer Service profile
One of the behaviors we want to check is that a person should not lose their temper when facing an irritated/angry/pesky customer.
A question:
We all have faced situations when we had to deal with an irritated/angry/pesky customer. Describe the worst customer you have faced. What made them the worst? How did you handle the situation? What was the outcome? What would you do differently? And more such probing questions.
For each behavior, at least use two situations.