Put the quinoa in a pan of cold water, bring to the boil and cook for 15–20 minutes or until the quinoa is translucent and just cooked. Drain and rinse thoroughly in cold water.
Meanwhile, make the dressing by mixing together the harissa paste, lime juice and rind and oil. Season to taste and set aside.
Mix the cooked quinoa with the prepared vegetables and herbs, 1 tablespoon of the sunflower seeds and the lime juice and rind.
Scatter over the physalis and the remaining sunflower seeds and serve with the dressing.