In a small bowl, whisk together the dressing ingredients.
Put the pumpkin seeds in a non-stick frypan and sprinkle with soy sauce. Cook them over moderate heat a couple of minutes until the soy sauce has dried. Set aside. In the same frypan, toast the almonds, making sure not to burn them.
Peel the orange, removing as much pith as possible, and cut into thin slices. If you can, add any juice that leaks out to the dressing.
Cook the chicken breast fillets. I prefer to do this on the barbecue but you can do it under the grill. You want them browned but not overcooked. Let cool just enough so you can handle them and shred into bite sized-chunks.
Divide the watercress over two plates, lay the chicken and orange over the top. Drizzle the dressing over, then scatter the pumpkin seeds and almonds on top of that. Serve immediately.