Directions

1. Make the salad: Preheat oven to 375 degrees. Puree garlic and oil in a blender until smooth. Toss with potatoes, tomatoes, and thyme on a rimmed baking sheet. Season with salt and pepper. Bake until potatoes are golden and tender, about 30 minutes. Let cool slightly.
2. Prepare an ice-water bath. Cook green beans in a large pot of boiling salted water until bright green and just tender. Transfer to ice-water bath. When cool, drain beans in a colander.
3. Make the dressing: Combine vinegar, mustard, thyme, and shallot in a small bowl. Add oil in a slow, steady stream, whisking until emulsified.
4. Toss potato mixture, beans, and arugula with dressing. Season with salt and pepper. Serve immediately or at room temperature.