Set 1 carrot at a time, flattest side down, between and parallel to 2 matching square dowels (plastic or wood) about 3/8 inch thick and 10 to 12 inches long.
With a sharp knife, make crosswise cuts down to dowels, 1/4 inch apart, along the length of the carrot. Then cut the carrot in half lengthwise through the center of the crosscuts and cut or break each carrot half into 4 or 5 equal pieces.
Put carrots in a 10- by 15-inch rimmed pan. Mix with 2 tablespoons olive oil and 1 1/2 tablespoons minced fresh ginger.
Bake in a 400° oven until carrots are well browned and taste slightly caramelized, 1 hour to 1 hour and 10 minutes (about 50 minutes in a convection oven). Turn often with a wide spatula and move pieces that are less cooked to perimeter of pan. Season with salt to taste.