1.Heat 2 tablespoons of the oil in a medium frying pan; add the mustard seeds. When they begin to crackle, add the cumin seeds and turmeric. Cook until fragrant, then add the onion; cook, stirring, for about 4 minutes or until golden. Add the ginger, garlic and capsicum; cook, stirring, for about 3 minutes or until capsicum is beginning to soften. Add tomatoes; cook, stirring, for a further 1 minute. Remove from the heat. Cover to keep warm.
2.Whisk together the eggs, mirin and soy sauce. Season with sea salt and freshly ground black pepper.
3.Heat a small non-stick frying pan (base measures 20cm) over medium heat. Add 1/2 teaspoon of the remaining oil. Add a quarter of the egg mixture; swirl the egg mixture to cover base. When the egg is set, slide the omelette out onto a warmed plate. Repeat with the remaining oil and egg mixture to make four omelettes.
4.Place omelettes on warmed serving plates. Spoon a quarter of the vegetable mixture over one half of each omelette, then fold the omelettes over the filling. Sprinkle with coriander.