For the dressing
Preheat the oven to 180°C, gas mark 4. Place all the vegetables on a large baking tray and add 1 tbsp of the olive oil and season. Roast for 30-40 minutes, or until tender and slightly caramelised. Place in the fridge until cool.
Cook the rigatoni according to the package instructions. Drain and toss with remaining 2 tbsp olive oil. Refrigerate until cool.
To make the dressing, combine the tahini, olive oil, garlic, lemon juice, salt and pepper in a food processor. While the motor is running, drizzle the cold water into the feed tube until you have a creamy but still loose consistency.
Toss all the ingredients together and place on a serving dish.
Sprinkle with the sesame seeds and micro greens.