Sauté the aromatics: Warm the olive oil in a large pot over medium heat. Add the onion with a pinch of salt. Cook 4–5 minutes until softened.
Stir in garlic and ginger and cook 30 seconds until fragrant.
Bloom the spices: Add turmeric, cumin, and black pepper. Stir for 30–45 seconds to release their flavor. Don’t let them burn.
Add cauliflower and liquid: Toss in the cauliflower florets and stir to coat with the spices.
Pour in the broth. The liquid should just cover the cauliflower; add up to 1 cup water if needed.
Simmer: Bring to a gentle boil, then reduce heat. Cover and simmer 12–15 minutes, until the cauliflower is very tender and easily pierced with a fork.
Blend until smooth: Use an immersion blender to puree the soup in the pot until silky.
Or carefully transfer to a blender in batches. Add a splash of water if you prefer a thinner texture.
Brighten and season: Stir in lemon juice and taste. Add more salt, pepper, or lemon as needed.
For extra creaminess, blend in yogurt or a small splash of light coconut milk.
Garnish and serve: Ladle into bowls and top with herbs, red pepper flakes, or pumpkin seeds. Serve hot.