Preheat the oven to 400°F and grease a large baking sheet with olive oil.
Chop the cauliflower and place it on the greased baking sheet. Put it in the oven and let cook for 30-35 minutes, flipping halfway.
Combine tahini, lemon juice, sesame oil, soy sauce, sriracha (if using) and water in a small bowl. Whisk until well combined. The sauce should be thick, but runny enough to drizzle over the cauliflower (taste and add more water and/or soy sauce as necessary).
Once the cauliflower is done, transfer half to a serving bowl and drizzle with half of the tahini dressing and a bit of parsley. Transfer the rest of the cauliflower to the bowl and drizzle with the rest of the tahini and parsley. Serve.
