Preheat oven to 180 °C.
Place cauliflower on a lined baking tray, drizzle with 2 tablespoons olive oil. Roast for 20-25 minutes or until golden and cooked.
On a separate lined baking tray, place wedges of red onion and almonds. Drizzle with 1 tablespoon olive oil and roast for 10-15 minutes or until golden.
To make dressing, combine tahini, lemon juice, warm water and parsley and whisk to combine.
In a large salad bowl gently toss roasted cauliflower, red onion, almonds, and rocket and drizzle with dressing. Serve warm.