1. In a large bowl, whisk together the tamari, honey or rice syrup and sesame seeds. Add the chicken breast and mix well, marinate for 5 minutes.
2. Meanwhile, peel and core the pineapple and chop into 1cm-thick slices. Heat a large frying pan or grill pan on high and cook the pineapple slices for 1 minute on each side. Remove from heat. Add the chicken to the pan, reduce heat to medium high and cook on each side for 5-6 minutes.
3. Slice the cos lettuce and divide between two serving plates then sprinkle evenly with quinoa. Cut tomatoes in half, scoop the flesh out of the avocado and arrange both on top of the lettuce along with the pineapple. Slice chicken into strips and transfer to the salads then sprinkle with sesame seeds.