In a large pot or deep skillet, heat the coconut oil over medium heat until melted.
Add the diced onion and sauté for about 5 minutes, or until softened and translucent.
Stir in the minced garlic and grated ginger, cooking for an additional minute until fragrant.
Add the curry powder, ground cumin, turmeric powder, and chili powder (if using) to the pot. Stir well to coat the onions with the spices and cook for another minute.
Introduce the cauliflower florets to the pot, stirring to combine with the spiced onion mixture. Allow the cauliflower to sauté for about 3-4 minutes.
Pour in the coconut milk, diced tomatoes, and vegetable broth (or water). Stir everything together and bring the mixture to a gentle simmer.
Reduce the heat to low, cover the pot, and let it cook for about 15-20 minutes, or until the cauliflower is tender and cooked through.
Add the chickpeas, salt, and black pepper, mixing gently. Cook for an additional 5 minutes to heat the chickpeas.
Remove the pot from heat and stir in the lemon juice for a bright finish.
Serve hot, garnished with fresh cilantro, alongside rice or naan.