In India there is a color coding system that one sees on all packaged goods and probably a majority of restaurant menus. A green dot in a square means the food is vegetarian (which means neither egg nor meat content in the product) and a red dot means non-veg.
Here in Thailand, at Khlong Toei Wet Market, it’s interesting to see how vendors used red and green awnings. In this case, it’s not so much to signify the product as to enhance its visual appeal. Vendors who specialized in green produce inevitably used green awnings to make their greens look greener. By the same token, meat vendors and fish vendors that specialized in “red fish” (e.g. tuna, as opposed to white fish, say halibut) used red awnings to make the reds redder. Incidentally, white fish and squid sellers often used a combination of white and blue tubs to create another kind of aesthetic appeal. Fruit vendors are out of luck because they have just too many colors to deal with. (Unless they specialized a single fruit like watermelon–or durian, because if you sell durian you’re out of luck on selling anything you don’t want tainted by the smell of durian.)
Lepény is a Hungarian street-food that some might call a folded over pizza and others might call a flat-bread sandwich. It’s bread (like pizza crust) topped with cheese and various vegetative and / or meaty toppings and cooked on a grill. (I just realized it could also be considered a fancy grilled cheese that starts from a ball of dough and not from pre-made bread.)
Anyway, there aren’t nearly as many lepény vendors as there are for say Kürtöskalács (the cylindrical sweet bread that is so very, very awesome), but the vendor at the Vörösmarty tér Christmas market always had a massive line. (We did discover that part of the long lines had to do with the temperamental nature of the wood-fired grills they used and the long time it took to cook one if they let the fire die down too much.) Still, people stayed in line, and that speaks somewhat to the tastiness of this treat.