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