Heat the oven to 400 degrees. Line a rimmed baking sheet with parchment (or don't if you're lazy like me and don't mind the extra caramelization).
Using your fingers, toss the vegetables with the oil, salt and thyme -- I do this right on the baking sheet so as not to dirty a bowl.
Put the vegetables in the oven and roast for 20 minutes. Flip them gently with a spatula and continue to roast until the vegetables are crisp and tender, another 10 to 20 minutes. Serve hot, warm or at room temp. (I like to keep a batch of these in the fridge all week so I can press them into service at any time.)