Cut the cauliflower into quarters through the stem. Trim and discard the core, then separate the head into florets. Place a third of the florets into a food processor and pulse in 2- to 3-second bursts until the cauliflower is finely chopped and has the consistency of couscous. Repeat twice, until all of the cauliflower is chopped. (One large head should yield approximately 8 cups chopped.)
Combine the cumin, pepper, turmeric, ginger and nutmeg in a small bowl and add 1 tablespoon water. Stir well to combine and set aside.
Heat the oil in a large saute pan over high heat. When the oil begins to shimmer, add the onion and cook, stirring often, until tender but not browned, 2 to 3 minutes. Stir in the garlic and cook until aromatic, 30 seconds more. Stir in the spice mixture and cook another 30 seconds.
Add the cauliflower, peas and carrots and stir well. Add some salt to taste. Cook, stirring often, until the cauliflower is tender, about 5 minutes. Transfer to bowls and garnish with chives.