Cook the carrots in a pan of boiling water for 3 minutes, then drain well.
Tip into a roasting tin and sprinkle with the thyme and fennel seeds. Drizzle over the olive oil and season with black pepper.
Roast the carrots in the oven alongside your joint, 20 minutes before the end of cooking time (they will be oven-cooked for 35 minutes in total, as you will be resting your joint for at least 15 minutes). Cook until tender and golden.