In a large bowl, combine the cauliflower and Jerusalem artichokes; toss them generously with olive oil and salt.
In a small bowl, combine the cumin and cayenne and add to the vegetables. Toss well to thoroughly combine.
Spread the veggies on a baking sheet in one even layer-use two baking sheets, if necessary. Roast 20 minutes, then stir the veggies so they have the chance to brown all over and rotate the pan to ensure even cooking. Roast another 20 minutes, then stir and rotate again.
Roast the vegetables for an additional 5 to 10 minutes, or until they are brown, tender and smell wonderful-almost like popcorn! If they aren't lovely and brown, let them continue to roast for another few minutes. Taste and adjust the seasoning, if necessary.
Remove the veggies from the oven, sprinkle with chives and transfer to a serving dish. Serve immediately.