Preheat the oven to 400 degrees F. Cut each potato into bite-size pieces. Lay them on a rimmed baking sheet and drizzle with a little oil. Lightly salt and pepper.
Shake the pan to spread the oil around. Then roast the potatoes for 30-40 minutes, until golden brown and tender. Make sure to flip once halfway through. Add the chopped garlic and shallots to the potatoes 5 minutes before they are ready to come out of the oven.
Once the potatoes and garlic are roasted, allow them to cool for a few minutes. Then toss them with the capers, fresh herbs, Dijon mustard and mayo. Mix well, and add 1-2 teaspoons caper juice to season and thin out the dressing if needed. *Be careful with the caper brine—it’s really salty! Cover and refrigerate until ready to serve.