Preheat the oven to 400 °F. Prepare the garlic by peeling and removing the outer layer. Cut 1/2 cm from the top of the cloves to expose them, wrap in foil, and bake for 40 minutes. Allow to cool.
Combine 2.5 tsp olive oil, harissa, turmeric, cumin, cornstarch, and a pinch of salt. Add the cauliflower and eggplant to this mixture, ensuring they are thoroughly coated. Transfer to a baking tray with the lemon and bake for 30 minutes.
While the vegetables are roasting, prepare the lentil mix by combining the lentils, 1/2 tsp olive oil, parsley, a pinch of salt, and dukkah.
For the dip, squeeze out the charred lemon juice and combine it with yogurt, roasted garlic, tahini, and a pinch of salt. Layer the dip, lentils mix, and roasted veggies to serve.