Boil the potatoes for 15 minutes until tender, then drain well and mash with the milk and 1tbsp olive oil. Dice the mozzarella and gently stir into the mash with the fresh basil. Do not overmix or the cheese will become stringy.
Meanwhile, heat 1tbsp oil in a shallow pan and add the sauce ingredients. Cook over a medium heat until the tomatoes soften to make a sauce.
Season the steaks and grill on high for 3 minutes each side for medium, 5 minutes on each side for well done.
Serve the sauce poured over the steaks with the mashed potatoes on the side.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home.