Preheat the oven to 210 C /400 F. Toss the cauliflower with salt, pepper, garlic powder and some oil. Spread evenly on a baking tray lined with baking paper. Roast for 40-50 minutes, until crispy and golden. It may be ready sooner, it varies depending on the oven, so start checking the cauliflower after the first 20 minutes.
In a large pot on medium heat, cook the onions in the oil, until they're slightly translucent. Add the garlic and all the spices, and stir constantly for 30 seconds to 1 minute, so they don't burn.
Add the diced cherry tomatoes, the diced red bell pepper, then the can of tomatoes, and stir to combine everything. Let it simmer for 5 minutes. Add the coconut milk, lentils, spinach and roasted cauliflower. Allow to simmer for 5 more minutes. Serve with basmati rice.