Just gently warm for a couple of minutes in the residual heat of the oven once you remove the tagine and cauliflower.
Spread the kale pieces on a large baking sheet lined with parchment. Sprinkle with the salt and drizzle with the oil, mix through with your fingers. Roast in the oven at 120C Fan/140c/gas 2 until just crisp and vibrant green- about 15 minutes- stir half way through so they crisp evenly