Preheat the oven to 200°C (400°F). Wash and cut 1 kg of cauliflower into medium-sized florets.
In a large mixing bowl, combine 3 tablespoons of olive oil, 1 teaspoon of turmeric powder, 1 teaspoon of red chili powder, 1 teaspoon of cumin powder, 1 teaspoon of coriander powder, 1 teaspoon of garam masala, salt to taste, and 1 tablespoon of minced garlic. Mix well.
Add the cauliflower florets to the spice mixture and toss until the florets are evenly coated.
Line a baking tray with parchment paper and spread the cauliflower florets in a single layer.
Roast the cauliflower in the preheated oven for 25-30 minutes, or until the florets are tender and golden brown. Flip the florets halfway through the cooking time to ensure even roasting.
Remove the roasted cauliflower from the oven and garnish with chopped coriander leaves. Serve hot.