How to Make It
Whisk the yogurt in a bowl. Stir in the tomatoes, cilantro and cayenne and season with salt and pepper. Refrigerate for about 1 hour.
Preheat the broiler. Set 1 pappadam in the center of a baking sheet as close to the heat as possible and broil with the oven door open until the pappadam begins to puff, about 5 seconds. Pull the baking sheet out of the oven and turn the pappadam 180 degrees. Return to the oven for about 3 seconds longer, or until the pappadam is dimpled and puffed. Transfer the pappadam to a wire rack and repeat with the remaining pappadams. Serve with the raita.