5 tablespoons extra-virgin olive oil
3/4 pound baby carrots or large carrots cut into 4-by-1/2-inch sticks
6 medium leeks, white and light green parts only, sliced crosswise
Salt and freshly ground white pepper
7 thyme sprigs
2 bay leaves, preferably fresh
Four 6-ounce skinless halibut fillets, about 1 inch thick