In a large mixing bowl, whisk together fresh lemon juice, corn starch, ground cumin, half of the ground turmeric and garam masala, and salt. Add the cauliflower florets and toss to coat. Set aside for 10 minutes.

Heat olive oil in a large skillet over medium-high heat. Add the coated cauliflower and sauté for 7-8 minutes until tender and slightly browned. Sprinkle with remaining corn starch mixture and cook for another 7-8 minutes until charred.

In the same skillet, lower heat and add remaining olive oil and unsalted butter. Sauté the chopped onion for about 8 minutes until translucent. Stir in minced garlic, ginger, and tomato paste for another 2 minutes.

Add the remaining turmeric, garam masala, and salt to the onion mixture along with paprika, ground cinnamon, and cayenne pepper. Cook for about 1 minute, stirring frequently to bloom the spices.

Pour in canned tomato sauce and vegetable broth, stirring to combine. Bring to a boil then simmer. Gradually stir in heavy cream and return cauliflower to the skillet. Simmer uncovered for 15 minutes.

Serve the Butter Cauliflower over basmati rice, garnished with cilantro and Greek yogurt.