Step 1 Preheat oven to 180°C. Line a large baking tray with foil. Place beetroots on tray and cover them with foil. Roast for 1 hour, until tender when pierced. Set aside to cool slightly, then peel (wear gloves to prevent staining) and cut into thin wedges.
Step 2 Meanwhile, spray a large frying pan with oil and place over high heat. Cook steaks for 2–3 minutes each side for medium, or until cooked to your liking. Remove, cover loosely with foil and rest for 3 minutes.
Step 3 Meanwhile, blanch broccoli until tender-crisp. Drain well. Place broccoli, beetroot, lentils, celery and parsley into a large bowl. Thinly slice beef and add to bowl. Drizzle with vinegar and toss gently to combine.
Step 4 Divide salad between serving plates, top with avocado and serve with toasted pita bread.