Preheat oven to 400 degrees F. Line a roasting pan or baking sheet with foil (if desired) and spray with nonstick pan spray. Place cauliflower in pan and drizzle with olive oil. Toss, or turn with a spatula, to coat. Sprinkle with salt and pepper and place in oven for 15 minutes.
2. Remove cauliflower from oven, sprinkle with minced garlic and toss, or turn, to coat. Return to oven for an additional 15 minutes, or until cauliflower is tender and becoming golden brown. Meanwhile, combine sesame oil, tahini, soy sauce, lemon, and cayenne in a small mixing bowl. Whisk sauce with a fork until smooth.
3. Remove cauliflower from oven and pour sauce over. Gently toss, or turn, to coat cauliflower in sauce. Remove to serving dish and garnish with chopped parsley or sesame seeds. Serve hot or at room temperature.