If the carrots are thick, cut them in half lengthwise. If not, leave them whole. Slice the carrots diagonally into 1 1/2 inch thick slices (the carrots will get smaller while cooking, so make the slices big).
Toss the carrots in a bowl with the olive oil, salt and pepper. Place on a baking sheet in one layer and roast in the oven for about 20 minutes.
Toss the carrots with minced dill or parsley, season to taste and serve.