I've never eaten two servings of bhel puri that have been exactly the same. The only things the various versions of this addictive Indian snack seem to have in common are puffed rice, small, crisp 'noodles' made of fried chickpea flour batter, and a tendency to become soggy quickly. Diced tomato and onion appear in most of the mixes; some also contain minced fresh coriander, fried lentils, peanuts and diced potato, and the flavourings range in degrees of spiciness (which come from minced fresh chillies or chilli powder) and sourness (usually from tamarind juice).
The best bhel puri I've had was bought from a vendor in Mumbai, who mixed the ingredients after asking if I liked chilli and sour flavours, then served the snack in a cone made of rolled-up newspaper. The deliciousness of the snack probably had something to do with the setting: I ate it at sunset while riding in a boat up one of the city's rivers. At the other end of the scale is the bhel puri served in restaurants, where the ingredients are laid out in separate piles on a plate and the diner mixes everything before eating it with a fork and spoon, rather than their fingers.