Preheat the oven to 425°F and line a baking sheet with parchment paper.
In a large bowl, toss the cauliflower florets with harissa paste, olive oil, salt, and black pepper until evenly coated.
Thread the coated florets onto the soaked wooden skewers, leaving a small space between pieces for even roasting.
Arrange the skewers on the prepared baking sheet in a single layer.
Roast for 25 minutes, flipping the skewers halfway through, until the cauliflower is tender and the edges start to brown.
While the skewers roast, whisk together tahini, lemon juice, and water in a small bowl until smooth and pourable.
Remove the skewers from the oven and drizzle with the tahini sauce.
Sprinkle with chopped parsley and sesame seeds before serving.