Pick your vegetables, use individually or several together. Here are vegetables that roast very well:

peppers (red, orange, yellow)
cauliflower
onions
sweet potatoes
potatoes
mushrooms
zucchini / yellow squash
acorn squash
carrots
asparagus

Heat the oven to 450 degrees.

Cut the vegetables to size; carrots, zucchini/yellow in sticks; acorn, sweet potatoes in small cubes (3/4 inch). The idea is to cut the vegetables in bit-size pieces that will cook sufficiently in 20 minutes.

Place all the vegetables in a big bowl, add olive oil, salt, pepper, tossing to coat. You may also decide to add garlic powder, thyme (fresh or dried), or other spices to this tossing.

Arrange in a single layer on a baking sheet (or more than one sheet if necessary to maintain a single layer). Roast for 10 minutes, stir and then roast again for 10 more minutes.