Combine lemon juice, corn starch, cumin, and 1/2 tsp each of turmeric, garam masala, and salt in a large bowl to create a flavorful marinade for your cauliflower florets.
Heat 1 Tbsp of olive oil in a large skillet over medium-high heat. Add the cauliflower florets and cook them, tossing occasionally, until they are browned in places and starting to soften, about 7 to 8 minutes.
Reduce heat to medium, transfer the sautéed cauliflower back into the bowl with the corn starch mixture, toss gently to coat them evenly, then return them to the skillet for another 7 to 8 minutes until they are charred in spots and crisp-tender.
In the same skillet, add remaining olive oil and butter; once melted, add finely chopped onions and cook until they turn translucent—this usually takes about 8 minutes.
Stir in garlic, ginger, and tomato paste; cook until fragrant for about 2 minutes before adding in remaining spices like turmeric, garam masala, paprika, cinnamon, cayenne pepper along with tomato sauce and vegetable broth.
Bring everything to a boil before reducing it down to a simmer; stir in heavy cream or coconut milk then add back your cauliflower florets into the skillet—simmer uncovered until thickened for about 15 minutes before serving hot over basmati rice garnished with cilantro and yogurt.