Step 1 Place potatoes into a large saucepan of cold water. Bring to the boil, then reduce heat and simmer for 15 minutes or until tender.
Step 2 Drain potatoes, then either crush lightly or cut in half. Return to saucepan then add onion, tomatoes, capsicum, parsley and olive oil. Toss gently to combine. Keep warm in saucepan until ready to serve.
Step 3 When ready to serve, place lettuce leaves into a serving bowl and top with potato salad. Toss lightly and serve with Garlic and mustard steaks.