Cook the quinoa in a pan of boiling water for 15 minutes. Drain and rinse through with cold water.
Meanwhile, make the dressing. Wipe the garlic halves around a clean bowl. Add all the other dressing ingredients and mix well. Combine with the quinoa.
In a separate bowl, lightly toss together the avocado, beansprouts, beetroot and watercress. Serve with the quinoa.