Step 1 Preheat oven to 200°C. Steam potato for 5–8 minutes, until tender. Transfer to a baking tray, spray with oil and roast for 20 minutes, until crisp.
Step 2 Meanwhile, combine oregano, oil and garlic in a shallow bowl. Add steaks and coat with mixture. Marinate for 10 minutes.
Step 3 To make salsa verde, combine mustard, capers, anchovies, parsley, coriander, lemon zest and half the lemon juice in a bowl. Stir until well combined.
Step 4 Place a large frying pan or chargrill pan over high heat. Cook steaks for 2–3 minutes each side for medium, or until cooked to your liking. Add remaining lemon juice to pan and remove from heat. Cover loosely with foil and stand 5 minutes.
Step 5 Serve steaks with salsa verde, potatoes, asparagus and tomatoes.