Preheat your oven to 425°F (220°C).
Wash, dry completely*, and cut the broccoli and cauliflower into bite-sized florets**.
Whisk together the tahini, soy sauce, maple syrup, lemon juice, minced garlic, dried Italian herbs, salt, and pepper in a small mixing bowl until creamy.
Add the broccoli and cauliflower to a large mixing bowl and pour the herbed tahini sauce over the vegetables. Toss until the vegetables are coated evenly.
Arrange the vegetables in a single layer on a big baking sheet (or two) lined with parchment paper***.
Roast the vegetables for 20-25 minutes, or until they are tender and lightly browned, stirring once halfway through.
Once done, remove from the oven and serve immediately. Top with chopped fresh herbs, sesame seeds, or crushed red pepper flakes, if desired.