To make the dough, place the flour into a mixing bowl. Gradually stir in 1/4 cup vegetable oil and the water to make a soft, pliable dough. Turn the dough out onto a floured work surface and knead until smooth, about 4 minutes. Transfer the dough to an oiled bowl, cover, and set aside for 1 hour.
Heat 1/2 cup of vegetable oil in a frying pan over medium-low heat. Sprinkle in the mustard seeds; when the seeds start to pop, stir in the green chile, ginger, onions, and curry leaves. Cook, stirring occasionally, until the onions are soft, about 5 minutes. Add the turmeric and a pinch of salt and cook for 1 minute more. Mix in the prawns and cook, stirring occasionally, until they are bright pink on the outside and the meat is no longer transparent in the center, 2 to 3 minutes. Remove from the heat and set aside.
Divide the dough into 8 equal portions. Place one piece in the palm of your hands and roll it into a smooth ball. Lightly dust with flour, then place it on work surface and roll out the dough into a paper-thin round about 8 1/2 inches (22 cm) in diameter. Repeat with the remaining dough.
Heat a cast iron skillet or heavy frying pan over medium heat. Brush the skillet with oil or use cooking spray.
Stir the beaten eggs into the prawn filling mixture. Place a circle of dough into the preheated skillet. Spread 3 tablespoons of filling over the dough. Cook until the bottom of the bread has browned, about 5 minutes. Lower the heat and carefully turn the paratha over with a spatula. Cook for an additional 5 minutes so the prawn mixture is well stuck to the paratha. Flip the paratha over again and transfer it to a cutting board.
Roll the paratha into a cylinder shape to enclose the filling. Repeat with the remaining dough and filling. Cut each stuffed paratha in half to serve.