Make the dressing.
Whisk the lemon juice, olive oil, salt and black pepper together until combined.
Divide between five quart-size wide-mouth jars, about 4 teaspoons per jar.
Layer the jars 3. Add the cooled quinoa on top of the dressing, then the diced chicken in an even layer. 4.
Add the cucumber and cherry tomatoes, then the feta and parsley. 5. Pack the baby spinach on top, filling the jar to the shoulder. Seal. 6. Store upright in the fridge for up to 4 days. Shake hard and tip into a bowl to serve.