Method

• 1.
  Combine harissa, 1 tbs oil, ½ tsp salt flakes and some freshly ground pepper on a large dish. Add steak and rub mixture all over. Leave to marinate and come to room temperature for 20 minutes.
• 2.
  Place potatoes in a saucepan, cover with cold salted water, bring to the boil, reduce heat to medium-low and simmer for 20 minutes or until tender. Drain and set aside to steam and cool briefly, then thinly slice.
• 3.
  To make a dressing, combine finely chopped herbs, both mustards, remaining oil, and lemon juice and zest in a screwtop jar, season and shake until emulsified. Add a third of the dressing to the warm potatoes and toss gently to coat. Place on a platter.
• 4.
  Heat a barbecue or chargrill pan to high, add steak and cook, turning once, for 4-5 minutes for medium rare or until charred and cooked to your liking. Place on a plate, loosely cover with foil, leave to rest for 5 minutes, then thickly slice.
• 5.
  Meanwhile, place zucchini, apple, pepitas and remaining herbs in a bowl, add half the remaining dressing, season and toss to coat. Place in a serving bowl.
• 6.
  Arrange steak on a serving platter, drizzle with remaining dressing and serve with potatoes and zucchini salad.