Scoop avocados into a bowl. Add juice, chile, salt, and garlic. Coarsely mash with a pastry blender or fork.
Cook oil and mustard seeds in a small covered saucepan over medium heat until seeds pop, 1 1/2 to 3 minutes. Remove from heat, stir in remaining spices, and let stand 2 minutes. Stir spice mixture and cilantro into guacamole. Serve with pappadums.
*Find pappadums (wafer crackers made from lentils) in the international aisle of well-stocked grocery stores; cook according to package directions.