Start this recipe by rubbing a little oil over the flank steak and season well with pepper and salt. Heat a griddle pan, add in a few thyme sprigs and quickly sear the flank steak on both sides for 2 minutes. Turn down the heat and continue to cook. Remove off the heat and allow to rest for 5 minutes. Meanwhile, in the same pan place in the onion and peach quarters and grill to caramelize. Meanwhile mix the dressing ingredients together. To serve, mix ½ of the dressing into the salad leaves and lay onto 2 large plates. Decoratively arrange the peaches, onions and gbejniet pieces over the salad leaves. Next, slice up the steak and arrange on top. Drizzle over the remaining dressing and serve.