Trim the fennel, peeling off outer strings. Cut it in ¼ in/6 mm slices through the root. Cook the fennel in a large pan of boiling salted water until almost tender, 10-15 minutes, and drain. Heat the oven to 350°F/175°C.
Heat the oil in a frying pan and add the lamb, garlic, coriander seed, salt and pepper. Cook, stirring constantly, until the lamb is browned a