Preheat the oven to 180 C (350 F). Line a baking sheet with parchment paper.
Cut the cauliflower into florets and the potatoes into bite size pieces. Transfer to a bowl and add the olive oil and lemon juice. Season with salt and pepper.
Tip the seasoned cauliflower and potatoes onto the baking sheet and roast for 35-40 minutes, turning once halfway through.
While the cauliflower and potatoes are roasting, start the curry. Add 1 tablespoon of olive oil to a medium size saute pan and saute the onion for 3-4 minutes, or until soft. Add the tomatoes, garlic, ginger, chilli peppers juice of remaining lemon and 2 tablespoon of water and continue sauteing for a further 5 minutes.
Add the spices and saute for a further two minutes.
Pour the coconut milk into the pan, add the chickpeas and give everything a good stir and allow to simmer for 10 minutes, or until the sauce has thickened.
Add the roasted cauliflower and potatoes. Garnish with fresh coriander.