Heat the oven to 425°F (220°C). Line a large, rimmed baking sheet with parchment if desired, or place the empty sheet in the oven for several minutes to help the cauliflower brown.

Cut the cauliflower into evenly sized, small bite-size florets. Dry the florets very well with a clean kitchen towel because surface moisture can prevent deep browning.

In a large glass, stainless-steel, or other nonporous bowl, whisk together the olive oil, turmeric, cumin, garlic powder, kosher salt, and black pepper. Stir in smoked paprika, coriander, or cayenne if using.

Add the dry cauliflower florets to the bowl and toss thoroughly until every piece is evenly coated in the golden spice mixture. Use a nonporous bowl because turmeric can stain plastic and other porous materials.

Arrange the florets on the baking sheet in one uncrowded layer, leaving space between pieces. Place the flat sides against the pan where possible for better contact and more browned edges.

Roast for 20 minutes, then carefully toss or turn the cauliflower. Continue roasting for 5 to 10 minutes, until the florets are tender when pierced and browned at the edges.

Transfer the hot cauliflower to a serving dish and immediately drizzle with fresh lemon juice. Scatter the chopped cilantro or parsley over the top, taste for salt, and serve with lemon wedges, yogurt, or tahini sauce if desired.