Heat the oven to 400°F/200°C. Bring a large pot of well-salted water to a boil. Add the cauliflower florets and cook until just tender, about 10 minutes. Drain thoroughly and spread on a parchment-lined rimmed baking sheet. Sprinkle evenly with the Parmesan.
Add the sweet potatoes to the same baking sheet, drizzle lightly with olive oil, and season with salt. Roast, turning once, until the vegetables are deeply golden and tender, 30 to 35 minutes.
Meanwhile, combine the cilantro, vinegar, honey, sugar, salt, olive oil, garlic, and water in a blender or food processor. Blend until completely smooth and bright green.
In a large bowl, combine the lettuces, cherry tomatoes, red onion, almonds, roasted cauliflower, and sweet potatoes. Add the dressing and toss gently to coat. Transfer to a serving platter and serve immediately.