Preheat the oven to 400 F and line a baking tray with parchment paper.
Pop the cauliflower florets, sliced red onion, garlic, olive oil, curry spice, lemon juice and salt into a bowl and toss it all together until the cauliflower is all coated in the olive oil and spice.
Spread the cauliflower onto the lined baking sheet and spread out a little. Bake for 20 minutes or until the cauliflower is browned and crispy on the edges.