Preheat the oven to 425 degrees F. Spread the cauliflower florets on a rimmed baking sheet, in a single layer. Drizzle with oil. Sprinkle with salt and shake the pan to coat with oil and salt.
Roast in the oven for 25-30 minutes. Shake the pan once or twice to turn the florets. Flip the stubborn florets with tongs.
Meanwhile place all the ingredients for the tahini dressing in a blender. Purée until smooth. If the dressing is too thick, add another 1-2 tablespoons water.
Serve the roasted cauliflower warm. Either drizzle the tahini dressing over the top or place in a bowl for dipping.