1 tbsp plus 1 tsp salt
12 oz green beans, trimmed
1 cup purple potatoes
1 tbsp Dijon mustard
2 tbsp red wine vinegar
6 tbsp olive oil
1 cup oven- roasted tomatoes
1/2 cup nicoise olives, pitted
1/4 cup sliced shallots
2 cups arugula
1/8 tsp black pepper

Bring a large pot of water to a boil and add 1 tablespoon of salt. Blanch the beans for 2 minutes, then plunge them immediately into ice water to stop the cooking. Drain and reserve them for later.

Place the potatoes in the same pot and cover them with cold water. Bring the water to a boil, then reduce it to a simmer. Cook the potatoes until they are knife-tender. Once cooked, drain the potatoes, let them cool completely and then halve or quarter them depending on their size.

In a large mixing bowl, whisk together the mustard and vinegar. While whisking constantly, slowly drizzle in the oil to emulsify the dressing. Add the green beans, potatoes, tomatoes, olives, shallots, arugula, the remaining 1 teaspoon of salt and the black pepper. Toss everything together and serve.