According to some websites that give interview advice, the teamwork example you give doesn’t have to be the typical answer we’d expect e.g. some sort of project at university or work. Instead it could be trivial things such as when you and your housemate cooked a meal for the rest of your housemates. As long as the example answers the question and is clearly explained then it should be okay.
I’ll be honest, I wouldn’t give an example when I was cooking in an interview and I had a similar problem in where I couldn’t think of any decent examples of working in a team. To remedy this I started signing up for voluntary work, participating in exercises that involved working with random people, and doing presentations etc so I could give more examples. I also found that after a while, a lot of my activities I could relate to a core competency so I made a note of it on my computer for future use.
Anyway I’m just saying I had the same problem and had no clear ideas, after a bit of practice, answers become more natural. I doubt many people would have never had to work with someone at one point in their time. Have you ever been on holiday with a friend? Organised a trip away? Participated in societies where you were given a task? Revised with a friend? Here’s some ideas but chances are you’ll have plenty of potential examples, you just need to remember them!
Oh and as another note; most answers like this should follow a guideline similar to STAR (Situation, Task, Action, Result).
So explain the situation, explain the task that was faced, what action YOU did and the result.
Hope this helps