In a small blender jar, add the shallots, garlic, Thai chilies, belacan, and 2 tablespoons anchovies.
Add some water into the jar and blitz into a smooth paste.
In a large wok over medium-high heat, heat the oil. Add a handful of anchovies and fry until golden. Remove from heat and set aside.
Add the blended ingredients and cook, stirring, until all the liquid has evaporated, 2 to 3 minutes.
Add the chicken and shrimp and cook, stirring, until just cooked, 1 to 2 minutes.
Add the oyster sauce and anchovy stock cube, and stir to combine.
Push the contents of the wok to the side, and add the eggs. Break up the yolks a little and let set, 30 seconds. Scramble the eggs.
Add the water spinach stalks and cook, stirring, until softened.
Add the water spinach leaves and cook, stirring, until wilted.
Add the rice and cook, stirring constantly, until thoroughly combined. Crank the heat up to high and keep cooking, until the rice starts to sizzle and is no longer moist.
Serve hot, topped with the fried anchovies and cucumber slices. A fried egg is also a very popular accompaniment.