Bring a medium saucepan of water to the boil with salt. Add in the potato and cook for 7 minutes. Add the beans to the saucepan and boil for 3 minutes. Remove the pan and drain.
Assemble the potato, green beans, baby spinach, tomato, olives and salmon in a bowl. Season with salt and pepper.
Whisk together the dijon mustard and olive oil.
Pour the dressing over the salad and toss to combine. Serve.