Preheat the oven to 400 degrees.
Toss cauliflower and eggplant with olive oil, salt and pepper, then spread out in an even layer on baking sheet. Roast for 25-30 minutes or until browned and tender, stirring halfway through.
In a small bowl, whisk together tahini, lemon juice, lemon zest, garlic and sea salt. Slowly add the hot water until you achieve the desired consistency.
Remove vegetables from the oven, drizzle with tahini dressing; and serve.