For the parathas, blend the flour, eggs, sugar, salt and condensed milk in a food processor (fitted with a dough blade) until well combined.
Gradually add the full-fat milk in a thin stream, blending continuously, until the mixture comes together as a soft dough.
Wrap the dough in cling film and chill in the fridge for at least one hour.
When the dough has chilled, turn it out onto a lightly floured work surface. Roll small, golf-ball sized pieces of the dough into balls using your hands, then roll them into thin discs using a rolling pin.
Brush the dough discs with melted butter using a pastry brush.
Fold one dough disc tightly into a concertina shape. (NB. Do not allow the concertina to fan out. The folds should be 1cm/½in apart.)
With the thinnest side of the concertina facing upwards, shape the dough concertina into a coil, tucking the outer end of the coil back into the centre of the coil.
Lightly squeeze the dough coil back into a ball, then roll it out using a rolling pin, until the disc is 0.5cm/¼in thick and 15cm/6in in diameter.
Repeat the process with the remaining pastry discs.
Heat the sunflower oil in a frying pan over a medium heat. Add the parathas one at a time and fry for 1-2 minutes on each side, or until crisp and golden-brown on the outsides and soft and flaky on the insides. Keep warm.
For the prawns in coconut, blend the onion, chilli, garlic and ginger to a paste in a food processor.
Heat the sunflower oil in a frying pan over a medium heat, add the curry leaves, mustard seeds and methi powder and fry for 20-30 seconds, or until fragrant.
Add the onion, chilli and garlic paste and fry for 1-2 minutes.
Add the water, turmeric and prawns and cook for 1-2 minutes or until the prawns are pink and the water has evaporated, stirring well to cover the prawns in the spice mixture.
Add the coconut milk and season, to taste, with salt and freshly ground black pepper. Bring the mixture to a simmer for 1-2 minutes, or until the coconut has warmed through and the prawns are cooked. Squeeze over the lime juice.
To serve, divide the parathas among four serving plates. Spoon the prawns in coconut alongside. Garnish with the chopped coriander and lime wedges.