Bring a large pot of water to boil. Add the chicken breasts, cover, and cook for 15-20 minutes. When the chicken is done, remove from heat, drain water, let cool, and shred with two forks.
Chop the cabbage into very thin pieces, like it would be for coleslaw. I did this by rolling up several leaves together and making thin vertical slices across the roll and then chopping them once horizontally. Peel and grate the carrots. Cut off the skin, remove the seeds, and peel the cucumber into ribbons. Roughly chop the coriander and spring onions. Toss the chicken and vegetables in a large bowl and keep chilled.
For the dressing finely chop the garlic and chillies and place in a small mixing bowl with the soy sauce, vinegar, agarve, lime juice, oil, and fish sauce. Whisk until smooth. Add the peanut butter and water and whisk again until smooth and creamy.
Toss the salad with the dressing. Add the crushed peanuts. Serve chilled. Leftovers can be stored in the fridge for up to one day. For best results, keep the leftover salad and dressing separate until ready to serve.
Dressing