Heat olive oil in a large pan over medium heat. Add onions, ginger, and garlic and sauté until onions are lightly browned. Add garam masala and turmeric, cook for 1 minute. Add the tomatoes and let simmer for 2 minutes.
Turn off the heat and use immersion blender to blend until smooth. If you do not have an immersion blender, wait for the sauce to cool before transferring it to a blender. Once blended with the blender, pour the sauce back to the pan. Heat back up to a simmer.
Add the coconut milk and salt, stir to combine. Add the frozen peas and cauliflower and stir to until they are evenly coated in the sauce.
Cover and simmer for 15 minutes, until the cauliflower is fork tender. Serve hot with basmati rice and garnish with cilantro.