In a large bowl, combine cauliflower, garlic, and lemon zest with the cumin, coriander, paprika, red pepper flakes, olive oil, kosher salt, and fresh ground pepper. Stir to coat evenly.
Line a baking sheet with parchment paper and place the cauliflower onto the sheet. Bake until tender, about 40 minutes, stirring occasionally.
To serve, squeeze over fresh lemon juice and if desired, add additional kosher salt to taste. Serve warm.