Methods

To make the puri

1. To make the dough, combine the flour, semolina, and salt in a medium bowl. Add the canola oil and, using your fingers, rub the oil into the dry ingredients. Add 1/3 cup water and gently bring the dough together. If the dough is too dry, add 1 tablespoon at a time until it comes together. You want the dough to be pretty stiff like papdi dough, not soft like chapati or roti dough. Turn out onto a clean surface and knead it a few times until it forms a ball, about 30 seconds. Wrap in plastic wrap and allow to rest at room temperature for at least 20 minutes.
2. Divide the dough into 3 pieces and cover 2 of the pieces with plastic wrap. Roll the remaining piece of dough out into a very thin round about 7-inches wide or 2 millimeters thick. Cut as many rounds as possible out of the dough with a 2 1/2-inch round cutter. Transfer the rounds to a baking sheet in a single layer, reserving the scraps.
3. Repeat rolling and cutting out the remaining 2 pieces of dough. Combine and press the scraps into a single piece of dough and let rest for a few minutes, then repeat the rolling and cutting process once more. 
4. Heat the 1" canola oil in a Dutch oven or large cast iron skillet over medium-high heat to 375°F. Meanwhile, fit a wire rack onto a second baking sheet or line the baking sheet with paper towels.
5. Fry 4 to 6 dough rounds per batch: Gently drop into the hot oil and fry, flipping halfway through, until golden-brown, 90 seconds to 2 minutes total. Using a slotted spoon or mesh spider, transfer the puri to the rack-lined baking sheet.

To make the pani

1. Combine cilantro, mint, green chillies, lemon juice, tamarind concentrate, chaat masala, ginger, black salt, if using, salt, and 1/4 cup water in a blender and blend on high until smooth. Add the remaining water and blend on low speed to mix. Taste and adjust seasonings, like chaat masala and salt. If it is a little too spicy, you can add a small spoonful of jaggery to balance everything out. If you want a smooth pani, you can strain through a fine mesh strainer.

To make the potato-chickpea filling

1. Mix all the ingredients together and season with salt, to taste.

To make the mango-avocado filling

1. Mix all the ingredients together and season with salt, to taste. If the mango isn't sweet enough, you can add a spoonful of jaggery, to taste.

Assembly

1. Arrange a bowl of the puri, a bowl of the pani with a handful of boondi added, the fillings, and the sev on the table. To assemble, take one puri and tap the top to break a small hole in the center. Spoon the filling of your choice in the middle, garnish with a sprinkle of sev, dip in the pani, and pop directly into your mouth!