Cauliflower, potato and pea curry - good enough for a main course but a great side dish

1/4 cup cooking oil

1 tablespoon ground coriander

1 1/2 teaspoons ground cumin

1/2 teaspoon turmeric

1/4 teaspoon dried red-pepper flakes

1 medium head cauliflower (about 1 pound), cut into large florets

1 1/2 pounds boiling potatoes (about 4), peeled and cut into 1 1/2-inch pieces

1 cup canned crushed tomatoes in thick puree

1/2 cup chopped coriander

1/2 cup water

1 teaspoon salt

1 cup frozen peas

In a large deep frying pan, heat the oil over moderate heat. Add the coriander, cumin, turmeric, and red-pepper flakes and stir.
Add the cauliflower and potatoes and cook, stirring frequently, until the vegetables start to soften, about 5 minutes.
Add the tomatoes, 1/4 cup of the fresh coriander, the water, and the salt. Bring to a simmer, reduce the heat to low, and cook, covered, until the vegetables are tender, about 15 minutes.
Stir in the peas and the remaining 1/4 cup coriander and cook, covered, until the peas are tender, about 2 minutes longer.