Preheat the oven to 425°F. Toss cauliflower and 4 Tablespoons of the olive oil on a rimmed baking sheet lined with parchment paper. Season with salt and pepper. Roast until tender and golden brown, 25-30 minutes.
Meanwhile, pulse parsley, lemon juice, lemon zest and remaining 2 Tablespoons of olive oil in a food processor until very finely chopped; season with salt and pepper. Toss roasted cauliflower with dressing and serve warm or cold.
Serve with roasted, grilled, or sautéed meat ... flank steak is my favorite. Mix any leftovers with quinoa, mixed salad greens, and toasted nuts with a fresh squeeze of lemon juice and little more olive oil.