Combine olive oil, balsamic vinegar, honey, mustard, garlic and salt and pepper in a screw-top jar. Shake well to combine.
Place steaks into a ceramic dish. Pour 1/3 of dressing over the steaks. Turn to coat. Refrigerate 30 minutes to marinate.
Place mushrooms into a bowl. Pour 1/2 the remaining dressing over the mushrooms. Toss to coat. Cover and set aside 20 minutes.
Preheat barbecue grill or char-grill on medium-high heat. Add steaks, cook, basting with marinade for 6 minutes on each side for medium or until cooked to your liking.
Add tomatoes, chickpeas, parsley and remaining dressing to the mushrooms, toss to coat. Season with salt and pepper and serve with steak.