1. Heat some oil in a frying pan and cook the onion and garlic over a medium heat with a sprinkling of salt until soft. Remove from the pan and keep to one side.
2. Put the breadcrumbs and milk in a large bowl and leave to absorb.
3. Put the cumin seeds and coriander seeds in a non-stick frying pan and cook over a low heat for a minute until lightly toasted then keep to one side. They’ll give off a really strong smell and this is when you know they’re done.
4. Once the milk has absorbed into the breadcrumbs, add the mince, onions and garlic, spices, lemon zest and half the chopped mint leaves to the bowl along with some salt and pepper. Use your hands to thoroughly combine everything.
5. Roll into meatball shapes around the size of a table tennis ball then fry in a pan with the remaining oil until browned on all sides.
6. Prepare the couscous by placing it in a heatproof bowl and rubbing the butter into it. Pour 600ml of just boiled water over the couscous then cover and leave for 10 minutes. Once the water has been absorbed, separate out the pieces with a fork and season with salt and pepper.
7. Stir the remaining chopped mint leaves into the yoghurt and then serve with the meatballs and couscous.