Toast curry powder and garam malasa in a small skillet over medium heat until fragrant, 1-2 minutes. Set aside for later.
Heat vegetable oil or coconut oil in a large sturdy Dutch oven over medium-high heat until it’s shimmering. Add onions and potatoes and cook until veggies start to brown, about 10 minutes.
Make a well in the center of the pan and add another tablespoon of oil if the pan is dry. Add garlic, ginger, chiles, and tomato paste to the center and for 30 seconds.
Stir in reserved, toasted curry and stir to combine. Add cauliflower and stir to combine. Continue to cook for a minute or two.
In a small food processor, pulse diced tomatoes with juice to make a light sauce. Add tomato sauce to pan along with water and chickpeas. Season with a big pinch of salt and stir together.
Increase heat and bring curry to a simmer. Reduce heat to medium, cover, and cook until cauliflower and potatoes are tender, about 10 minutes.
Stir in peas and coconut cream. Season to your liking. Serve curry over cooked basmati rice.