Can I serve this salad warm or cold?

Yes. Serve it warm right after roasting and tossing with barley and dressing for a cozy main, or chill it and serve cold for lunches — both work well because the barley holds its texture.

What protein additions work well?

Chickpeas (roasted or plain), crumbled feta, or sliced grilled chicken are all good choices to make this salad more filling while keeping the flavors balanced.