For the filling, mix the fish sauce, sugar, pepper and tomato ketchup in a small bowl.
Heat the vegetable oil in a frying pan or wok over medium-high heat. Add the garlic and onion and stir-fry until soft. Add the pork and stir-fry until almost cooked. Then add the fish sauce mixture. Stir-fry for another minute or until the pork is cooked. Then add the tomatoes and stir-fry until well combined. Remove from heat.
To make the omelette, whisk eggs with 4 tablespoons of water. Place a non-stick pan (approx. 22cm in diameter) over medium heat.
When the pan is hot, add the oil and swirl to coat the pan. Pour in the eggs and use a spatula to keep spreading out the eggs until they’re firm. Add half of the filling mixture to the centre of the omelette.
Fold the edges of the omelette over the filling. Remove from heat and transfer to a serving plate. Serve with Coconut Sriracha or your choice of spicy sauce or extra ketchup.