Preheat the oven to 425°F. Lightly oil a baking sheet or coat it with nonstick spray. Arrange the carrots cut-side down in a single layer. Drizzle with olive oil, season with salt and pepper, and toss gently to coat. Roast for 15 minutes. Remove the tray from the oven, drizzle the carrots with maple syrup and continue roasting until they’re tender, 5–8 minutes more. Take the carrots out of the oven, sprinkle with pistachios, add a splash of vinegar and serve.