1. Fill a medium pot with cold water. Add the potatoes, garlic, rosemary, thyme, caraway seeds and 2 teaspoons salt. Cover, then bring to a boil over medium-high heat. Cook the potatoes until a paring knife easily slips into the center of one of the larger potatoes, 10 to 12 minutes. Strain through a colander or fine-mesh sieve and discard the garlic, rosemary and thyme. Once the potatoes are cool enough to handle, slice into ¼-inch-thick rounds and place in a large bowl.

2. Meanwhile, in a small skillet set over high heat, add the beef broth and onion. Bring to a boil. Turn off the heat and pour the hot broth-onion mixture over the potatoes.

3. In a small bowl, whisk together the vinegar, sunflower and olive oils, and mustard, then pour over the potatoes and gently stir to combine. Finish with salt, some grated nutmeg and white pepper. Set aside to cool, stirring occasionally, until the potatoes are at room temperature, about 30 minutes. Sprinkle with chives and serve.