Step 1Preheat oven to 180°C. Line 2 large baking trays with baking paper. Place sweet potato on one tray and drizzle with half of the oil. Season with cracked black pepper. Bake for 40 minutes, or until just tender.
Step 2Meanwhile, heat remaining oil in a large non-stick frying pan over medium-high heat. Cook beef for 1 minute each side, or until browned all over. Transfer beef to second tray and set aside.
Step 3Return same pan to heat. Sauté onion for 5 minutes, or until tender. Add garlic, mushrooms and thyme leaves. Cook, stirring occasionally, for 5 minutes, or until mushrooms are browned.
Step 4Press mushroom mixture over beef. Bake for 6–7 minutes, for medium, or until cooked to your liking. Remove, cover loosely with foil and rest for 2 minutes.
Step 5Meanwhile, whisk lemon juice and remaining oil in a salad bowl. Add lettuce, pear and walnuts. Toss gently. Serve the beef with wedges and pear salad.