Squash, chicken & couscous one-pot

INGREDIENTS

• 2 tbsp harissa paste
• 1 tsp each ground cumin and ground coriander
• 2 red onions , halved and cut into thin wedges
• 2 skinless chicken breasts , cut into bite-sized chunks
• 1 small butternut squash , cut into 1cm chunks (no need to peel)
• 2 x 400g cans tomatoes
• zest and juice 2 lemons
• 200g cherry tomatoes , halved
• 140g couscous
• small bunch coriander , roughly chopped