Combine yoghurt with zest and juice of one lemon in a small bowl.
Place rocket into a separate bowl. Chop mint and add half to bowl with rocket. Toss to combine.
Combine remaining mint in a shallow bowl with zest of remaining lemon. Season with black pepper. Add chicken, pressing to coat both sides with mint mixture. Transfer to a board. Cover with a sheet of baking paper and flatten to 1cm thick using a rolling pin.
Heat oil in a large frying pan over high heat. Cook chicken for 3 minutes on each side or until golden and cooked through. Transfer to a plate.
Add peas, snow peas and sugar snap peas, stirring for 1 minute to warm through. Add to bowl with rocket and toss with half the yoghurt dressing to combine. Slice chicken and serve with salad, toasted sourdough and remaining dressing drizzled over the top.