Step 1 Preheat oven to 180°C. Place chicken in a large bowl with half of the ground spices; toss to coat. Cover bowl and place in fridge to marinate for 30 minutes.
Step 2 Spray a flameproof casserole dish (that has a tight-fitting lid) with olive oil; set over medium heat. Cook chicken, in 2 batches, for 3–4 minutes, or until browned. Remove from heat and set aside.
Step 3 Return dish to medium heat; spray with oil again. Add onion and cook, stirring occasionally, for 5 minutes, or until soft. Add remaining ground spices, garlic and ginger to dish; cook, stirring, for 1 minute. Add cauliflower and cook for another 2 minutes. Add basmati rice, stir to combine and cook for 1 minute. Add stock with 1 cup water, bring to the boil and add chicken in a single layer. (Do not stir to combine.)
Step 4 Cover dish and cook in oven for 30–35 minutes, or until rice is tender and has absorbed liquid. Remove dish from oven and set aside to steam for 5 minutes.
Step 5 Meanwhile, mix tomato and fresh coriander to make salsa; season with black pepper. Top biryani with salsa and serve.