Couscous-stuffed zucchini with harissa yoghurt

Ingredients

• 4 medium zucchini, halved lengthwise
• 1/2 cup couscous
• 1 tablespoon vegetable or olive oil
• 1 small white onion, finely chopped
• 8 dates, pitted, coarsely chopped
• 1 teaspoon finely grated lemon zest
• 2 tablespoons flaked almonds, toasted
• 2 tablespoons shredded mint
• pinch of ground cinnamon
• 1/3 cup grated tasty cheese
• 1 teaspoon harissa
• 1/2 cup greek-style natural yoghurt
• lemon wedges, to serve