To make the meatballs, put the mince, ras el hanout, egg and parsley in a bowl and season. Mix together to ensure all the ingredients are well combined, then shape into 12 balls. Transfer to a plate, cover with clingfilm and chill for a minimum of 30 minutes.
Meanwhile, make the couscous. Put the golden beetroot in a food processor and blitz until it resembles very small couscous-like grains. Transfer to a bowl and repeat the process with the red beetroot, transferring to a separate bowl, so the colours don’t bleed. Heat a frying pan over a medium heat and mist with an olive oil spray. Cook the golden beetroot for 4-5 minutes, or until the beetroot has softened but still retains a bit of bite. Transfer to a bowl and repeat with the red beetroot. Leave both to cool to room temperature, then toss gently together along with the herbs. Season and set aside.
Heat a frying pan over a medium-high heat and spritz with olive oil spray. Cook the meatballs for 8-10 minutes, turning frequently to ensure they are browned evenly on all sides.
Mix together the Greek yogurt and lemon juice. To serve, divide the couscous between 4 serving plates, top with 3 meatballs and drizzle with yogurt. Top each plate with a little dollop of harissa.