Rinse the quinoa under cold water. Wash the bok choy and cut the white stems into strips and chop the green leaves roughly. Keep the white and green separate. Finely chop the garlic and grate the ginger. Pat the prawns dry with kitchen paper.
Bring the quinoa and water to a boil in a pan. Turn the heat to low, put the lid on the pan and let it simmer gently for fifteen minutes until all the water is absorbed. Remove the pan from the heat, leave it covered for five minutes and fluff the grains with a fork.
Heat the sunflower oil in a wok over high heat. Fry the garlic and ginger for half a minute. Add the prawns and cook them for about two minutes until pink and cooked through. Remove the prawns from the wok and set aside.
Fry the white stems of the bok choy in the hot wok for two to three minutes. Add the green leaves and stir-fry for another minute until wilted. Return the prawns to the pan and stir in the soy sauce and sesame oil. Warm everything together for another half minute.
Divide the warm quinoa over the plates. Spoon the hot wok vegetables and prawns directly on top.