Step 1 Preheat oven to 190°C. Heat half the olive oil in a large, deep saucepan set over medium heat. Add onion and garlic; sauté for 2–3 minutes, or until soft.
Step 2 Dust steak with flour and black pepper. Add floured steak to pan and cook for 3–4 minutes, or until browned on all sides. Add beef stock, tomato purée, mushrooms, zucchini, potatoes and rosemary; simmer for 1 hour. Remove pan from heat and leave to cool.
Step 3 Blitz a quarter of the cauliflower in a food processor until texture resembles fine rice; transfer to a medium bowl. Repeat process with remaining cauliflower. Add remaining olive oil to bowl; stir until mixture is well combined.
Step 4 Grease 6 x 1 1/2-cup-capacity pie dishes. Divide beef filling among dishes. Spoon cauliflower mixture over filling and spray with olive oil. Transfer dishes to oven and bake for 40 minutes, or until golden. Remove pie from oven, leave to cool for 5 minutes and serve.