Heat vegetable oil in a large frying pan over medium heat and stir in onion and carrot until the carrot becomes tender. Add chicken and cook until it is fully cooked.

Add the rice and combine with the vegetables. In a small bowl, combine together the ketchup and water. Pour the ketchup water and soy sauce to the frying pan. Stir until everything is fully incorporated. Turn off the heat.

Scoop the fried rice to a bowl for serving. Set aside.

In a medium bowl, whisk the eggs, milk, and salt until the mixture is uniform in color.

Heat butter in a large non-stick pan over low-medium heat. Swirl the butter to coat the pan evenly.

Pour the egg mixture to the pan. Immediately scramble it with a chopstick in small swirls to form curds. Then, scrape down the edges with a spatula.

Once the egg has set but still looks slightly runny, remove the pan from the heat.

Flip the fried rice bowl to a plate. Gently slide the egg on top of the fried rice. Drizzle with ketchup and mayonnaise. Garnish with seaweed flakes. Serve immediately.