Liking Mango Verde con Pepita (green -not ripe- mango with pepita) is probably one of those things that make you a Guatemalan, right up there next to the beans. Pepita o pepitoria is grained pumpkin seed.
Mangos green and ripe are commonly sold on fruit street carts and served in a plastic bag with pepitoria, salt, lemon and chile if you so desire. The sanitary standards are questionable.
Yesterday at the mall I decided to try a new food stand that is taking the street cart to a new level. They are selling selling fruit and vegetables with pepitoria in a clean and attractive way. I got this this very chapin snack for Q15.00 a cup.
You might be able to get pepita or pepitoria at your local hispanic market. The taste between country of origin will vary according to the type of pumpkin used. Mexicans usually sell a blend of pepitoria, salt and chile with a similar taste.
Try it with apples, oranges, or cucumbers. I always add lemon.
You can buy pepita in the US, here.