What you have to do is pick a country with a hot climate and see what they eat.
Here is a good example:
http://www.thespicespoon.com/blog/ab-doogh-khiar-cucumber-soup-in-the-persian-manner/
(i'm sure recipes differ)
It is basically a chilled yoghurt based soup, it is really tasty and refreshing on a hot day. Ours tends to have: yoghurt, water, raisins, mint, radish, spring onion, (walnuts - normally added but I'm allergic) and then bread to add before eating. It's quite filling too.
edit: After talking about it my Dad made it for his lunch.
I could do with that tonight, instead we're having hot chicken soup... :<
edit:
Salad niçoise is always good; grill/bbq some tuna fillets, new potatoes, lettuce, anchovie, olives, green beans, egg.
Honeydew melon with feta cheese or parma ham is nice as well.
Wraps. Plenty of salad and then some chicken or steak.. or just salad!
For something as a side, mushrooms mixed with dijon and wholegrain mustard is quite nice.