Give the vegetables room
Choose a sturdy, rimmed sheet pan and spread the vegetables in one layer. When pieces are crowded, their moisture collects and they soften before their edges can brown.
Cut the pieces to a similar size. Dense vegetables such as carrots and potatoes need smaller pieces than quick-cooking onions or squash.
Let the oven do the work
A hot oven, around 220°C (425°F), helps the outside color while the center turns tender. Toss with just enough oil to lightly coat, then turn once when the underside has begun to brown.
If the tray looks dry, add a small drizzle of oil; if liquid is pooling, move the vegetables farther apart or use a second tray.
Finish while warm
Taste before serving. A squeeze of lemon, a little flaky salt or fresh herbs can brighten the natural sweetness without hiding it.
For a mixed tray, add delicate herbs, maple syrup or a soft cheese near the end so they do not scorch in the oven.
