Combine all the dressing ingredients in a bowl and whisk well. Set aside.
Cook orzo in boiling water until just done, about 12 minutes. Drain.
Meanwhile, fry the chicken breast about 4 minutes per side. Remove from the pan and thinly slice.
In a salad bowl, combine the orzo, chicken, cucumber, capsicum and spring onions. Drizzle the dressing over and toss. Sprinkle with feta cheese and serve.