Prepare the rice according to package instructions. Spread it onto a large baking tray, cover it, and refrigerate overnight to chill.
Combine the onion, garlic, and sambal oelek in a small food processor and blend until smooth.
In a sizzling wok, heat up 1 tablespoon of oil until it shimmers. Add the chicken and stir-fry until golden, about 5 minutes. Transfer to a plate. Next, toss in the prawns and stir-fry until they curl and turn pink, about 3 minutes. Transfer to the plate with the chicken.
Drizzle 2 tablespoons of the reserved oil into the wok over low heat. Cook the onion mixture, stirring frequently, for 10 minutes until it turns a rich, dark red. Turn up the heat to high, stir in the rice, kecap manis, and soy sauce, and stir-fry for 5 minutes until the rice is heated through.
Combine chicken and prawns in the wok, toss together, and transfer to a large bowl. Cover to keep warm.
In the wok with the remaining oil, gently crack and cook 2 eggs for about 3 minutes until whites are set and yolks are nearly cooked to your preference. Transfer to a plate and repeat with the remaining eggs.
Spoon the rice onto serving plates and arrange the cucumber, tomato, and fried eggs on top. Serve with prawn crackers and sweet chilli sauce on the side.