1Whisk olive oil, vinegar, honey, mustard and salt and pepper in a large bowl. Remove 2 tablespoons to a small bowl and set aside. Add the mushrooms to the large bowl and stir to coat. Cover and set aside 1 hour to absorb the marinade.
2Meanwhile wash the beans and place onto a microwave-safe plate. Cover with damp paper towel and microwave for 1-2 minutes until bright green and just tender. Refresh in iced water, drain and pat dry. Halve the beans if necessary.
3Heat walnuts in a non-stick frying pan over medium heat, until lightly toasted. Add the sesame seeds and cook a further 1-2 minutes until golden.
4Add the beans, tomatoes and chickpeas to the mushrooms. Pour over the reserved dressing and toss to combine. Spoon onto a plater, scatter over walnuts and sesame seeds. Serve.