Combine all of the ingredients for the marinade in a shallow dish and whisk to combine. Add the tempeh slices and marinate for a couple of hours or overnight, turning the pieces of tempeh now and again.
To make the tzatziki, combine all of the ingredients (except for the cucumber) in a food processor and process until smooth. Pour the mixture into a container or bowl, and stir in the diced cucumber. Store in the refrigerator to marinate for a couple of hours.
When ready to eat, heat a skillet and add a splash or two of vegetable broth. Brown the tempeh on both sides, adding a little more broth or water as necessary. Add to the lettuce wraps, and add the Kalamata olives, red onion and parsley, and a generous drizzle of the tzatziki.