Originally the food truck concept started in America, where this form of street vendors has become quite common. Some media think that the food truck idea has already been exhausted, but development is still happening.

When it first started it was mostly (unhealthy) fast food, but in the meantime there are numerous food trucks that are offering healthy food items. We show five of the best 26 healthiest food trucks, published by the American blog ‘Greatist'. 

1. Let’s be frank

Hot dogs are not often healthy, but not at Let’s be frank. Their hot dogs are made from grass-fed animals, free of hormones, antibiotics and nitrates. Let's be frank supports farmers in California, where cattle is free to roam on grass fields, since these provide more vitamin A, E and Omega 3 in the meat.
www.letsbefrankdogs.com

2. Momogoose

Food truck Momogoose in Boston was well ahead of its time. This truck has been in existence for over twenty years! The name Momogoose comes from Goose and Momo. Goose comes from the owners of the old restaurant Poppa and Goose. Momo is an abbreviation of More eating, More sharing. Here, everyone can find something he or she likes, vegetarian, vegan, non-vegetarian, it's all available. Nice to note that the more Momogoose sells the more they donate to charity. 
www.momogoose.com

3. Green Truck

The Green Truck means being green, because the food they sell as well as the truck is 'green'. Recycled vegetable oil from the cooking the day before is used to move the truck and solar panels are used for extra energy. The packaging material they use is all recyclable. But also the green meals they serve are quite delicious. 
www.greentruckonthego.com

4. GMonkey

GMonkey is a vegetarian, eco-friendly food truck (drives on bio-fuel) that buys as much ingredients as possible from local farmers and local producers. The name GMonkey derives from sustainability, 'green' and the high intelligence and vegetarian eating habits of monkeys.
www.gmonkeymobile.com

5. Hola Arepa

If you are a fan of South-American food you are in for a treat. This food truck offers almost nothing else but sustainable South-American products, specializing in Venezuelan areas, buns made with cornmeal dough, filled with different ingredients like beans, sauces, cheeses and vegetables. Hola Arepa only uses local and organic meat.
www.holaarepa.com