Place a large rimmed baking sheet on the center rack of your oven and preheat the oven to 425°F.,

While the oven preheats, halve the potatoes and toss them with 1 tablespoon of the olive oil along with the salt and pepper. If you have some potatoes that are especially large for the baby variety, quarter them.,

Remove the preheated pan from the oven and carefully line it with a piece of parchment paper. Pour the potatoes out onto the prepared pan and spread them into an even layer. Roast until the potatoes are golden brown and fork-tender, 15 to 20 minutes, stirring once halfway through cooking.,

Meanwhile, in the bottom of the same bowl used to toss the potatoes, prepare the dressing by whisking together the pickle brine, shallot, Dijon, and the remaining 2 tablespoons of olive oil.,

Add the roasted potatoes and parsley and toss to combine. Taste for seasoning, adding salt if needed. Transfer to a serving platter, garnish with the pickles, and serve.