zhang quan is aware of the contradidictions.. does he think china can play a leading role in climate protection? the engineer from ningxia is certain it can. he says he's surrounded by proof of it every day. host: today's global snack comes from tunisia. enjoy. reporter: tunis -- capital and political center of tunisia. some two million people live in the greater metropolitan area, in a city that's both modern and traditional. in the city's center is the sahfa toun, named after the snack made here. the snack bar is an institution, with only one thing on the menu. safha toun is made from olive oil, egg, a lot of garlic, and harissa -- a hot paste made from chili, cumin, coriander seed, garlic, salt, and olive oil. with that, you get tuna and a choice of toppings like cheese or salami. a plate costs between 40 cents and 1 euro 40. most of the customers have been shopping or work in the area. >> it's great for your health. and it's full of tasty things, and it's just packed with garlic. >> safha toun is really substantial -- it fill