Peel and chop the onion. Peel and grate or crush the garlic. Finely grate the zest from the lemon and squeeze the juice. Rinse and roughly shred the chard.
Heat a splash of olive oil in a large pan. Add the onion. Fry gently over a medium heat for 10 mins. Add the garlic and fry for another 2 mins.
Stir in the cumin and harissa and cook for 1 min.
Fill the kettle and boil it. Drain and rinse the chickpeas. Add to the pan with the couscous and 600ml hot water from the kettle. Season with salt and pepper. Stir well. Bring to the boil.
Cover and simmer gently for 10 mins till the couscous is cooked. Stir occasionally.
Add the chard add to the pan. Cover and cook for 2 mins over a medium heat till tender.
Stir in the lemon zest and juice. Taste the stew and adjust the seasoning if needed.
Spoon the stew into large warm bowls to serve.