Preheat the oven to 200°C (392°F) using top and bottom heat with fan assistance.
Clean the cauliflower, cut it into florets, and place them on a baking tray lined with parchment paper.
Dice the feta cheese and add it to the cauliflower. Sprinkle with the seasonings, drizzle with olive oil, and toss everything together thoroughly.
Roast in the oven until golden brown, about 10-15 minutes.
Meanwhile, prepare the couscous. Bring the water to a boil in a saucepan, add the salt and couscous, and stir well. Remove from the heat and let it steam under a lid until the cauliflower is ready.
Mix the dressing ingredients together in a bowl.
To serve, place the couscous on one side of the bowl and the roasted cauliflower with feta on the other side. Add diced cucumber, tomato, and lettuce leaves. Drizzle with the dressing and enjoy while still warm.