Preheat the oven to 400 degrees.
If the carrots are thick, cut them in half lengthwise; if not, leave whole.
Slice the carrots diagonally in 1 1/2-inch thick slices. (The carrots will shrink while cooking so make the slices big.)
Toss them in a bowl with the olive oil, salt, and pepper.
Transfer to a sheet pan in 1 layer.
Roast in the oven for 20 minutes, until browned and tender.
Toss the carrots with minced dill or parsley, season to taste, and serve.