To cook the quinoa, combine with all the ingredients except for the peas in a saucepan and bring to a simmer. Allow to cook until the water has been absorbed then turn off the heat, add the peas and cover with a lid. Allow to steam for 10 minutes. Allow to cool to room temperature.
For the chicken, combine all the ingredients and allow the chicken to marinade for 10-30 minutes.
Grill/pan-sear the chicken until just cooked and golden brown on both sides. Remove from the pan and allow to cool to room temperature before slicing.
To make the salad, combine the cooked and cooled quinoa mixture with the feta and peas then dress with olive oil and lemon and season to taste.
Serve topped with the sliced chicken and cucumber.