Toss cauliflower florets with 1 tablespoon olive oil and a pinch of salt. Roast on a rimmed baking sheet until fork tender and caramelized, about 20 minutes. Cool completely.
Add roasted cauliflower, tahini, garlic, lemon juice, salt, and olive oil to food processor. Process until mixture reaches hummus consistency. Taste and adjust seasonings. Add water, if needed, to thin.