I made this for a client today, and it's got so much going for it: it's cool and refreshing, surprisingly hearty and really flavorful.
My client doesn't eat dairy, so I used soy sour cream. I also changed up the recipe by using 1 1/2 pounds of shrimp for four main-dish servings, which I sauteed in the oil called for. I tossed the cooked shrimp with ground cumin (the client can't tolerate seeds), lemon zest, salt and pepper.
The finished product was an absolutely perfect hot summer day dish.
Great news: If tomorrow's forecast is hot and steamy (or company's coming for lunch or dinner), make the recipe a day ahead: each of the elements of the dish can be prepared ahead of time, and then assembled in the bowl prior to serving. Which will leave you as cool as a cucumber (or zucchini) come dinnertime.