2 heads cauliflower (4 pounds), cut into 1 1/2-inch florets
2 medium onions, halved lengthwise and thinly sliced crosswise
Salt and freshly ground pepper
1 teaspoon turmeric
1/2 teaspoon cumin seeds
1/2 teaspoon cayenne pepper
One 4-inch cinnamon stick
2 cups tomato puree
1 cup water
1 1/2 cups frozen baby peas
In a very large, deep skillet, melt the butter. Add the cauliflower and cook over moderately high heat until browned in spots, about 5 minutes. Add the onions, season with salt and pepper and cook until softened, about 2 minutes. Stir in the turmeric, cumin seeds, cayenne and cinnamon stick and cook until fragrant, about 1 minute. Add the tomato puree and the water and bring to a simmer. Cover and cook over moderately low heat until the cauliflower is tender, about 15 minutes.
Stir in the peas and cook uncovered over moderate heat until the sauce is thick, about 5 minutes. Discard the cinnamon stick and season the cauliflower with salt and pepper. Transfer the cauliflower to a bowl and serve hot or warm.
The cauliflower in tomato sauce can be refrigerated overnight.