Preheat the oven to 400°F (200°C).
Put the cauliflower florets in a bowl, drizzle with olive oil, and season with salt; toss to coat.
Spread the cauliflower in a single layer on a cookie sheet and roast in the hot oven for 30 minutes, turning occasionally, until the florets are browned and tender.
While the cauliflower roasts, whisk together the minced garlic clove, the juice of 2 lemons, the splash of olive oil, and salt in a small bowl to make the lemon dressing.
Remove the roasted cauliflower from the oven, transfer it to a mixing bowl, pour the lemon dressing over the cauliflower, and toss to coat evenly.
Serve immediately.