In batches, break up the florets into a food processor and pulse until the mixture resembles couscous. Add the carrot to the processor and pulse to the same consistency.
Heat the oil in a large skillet over medium-high heat. Add the onions, and stir to coat. Cook until the onions are golden brown at the edges and have softened, about 7 minutes. Add the cauliflower, carrot, and stir to combine. Add salt, and continue to cook, stirring frequently, until the cauliflower has softened, 3 to 5 minutes. Remove from the heat. Add the lemon, parsley, and season to taste with salt. Stir to combine. Serve warm.
