This recipe looks light, easy and tasty:

http://www.kitchendaily.com/recipe/grilled-harissa-chicken-with-cucumber-yogurt-dressing-151501

I would do this without the lengthy marinade and just rub the breast with everything but the yogurt.

If Greek yogurt is too pricey, get some cheesecloth and strain store brand fat free unflavored yogurt for a couple of hours (line a colander or large mesh strainer), no one will know the difference.