Fingerling potatoes are often confused with new potatoes due to their small size and thin, tender skin. However, fingerlings are fully mature potatoes with an earthy nuttiness. Roasting is a great way to enhance their flavor with browning, and their diminutive size means they can be cooked whole. The only problem is that they can vary widely in shape (from crescent‑like to knobby) and length (from 1 inch to nearly 5 inches). I wanted to see if I could get assorted sizes to cook at the same rate.
I started by tossing 2 pounds of fingerlings with salt and a few tablespoons of vegetable oil, spreading them on a rimmed baking sheet, and placing the sheet in a 450-degree oven. Thirty minutes later, the potatoes had deep patches of browning and the smaller ones were cooked through, but in general the skins were tough, and some of the larger spuds were still firm in the center. At such high heat, the exteriors were drying out before the larger potatoes had a chance to cook through. In addition, the potatoes weren’t covering the entire baking sheet, allowing the residual oil on the sheet’s exposed surface to polymerize in the hot oven—and polymerized oil is very difficult to clean. Instead, I moved the fingerlings to a 13 by 9-inch metal baking pan, where they fit snugly in a single layer.
I knew that crowding the potatoes would cause them to steam a bit, but that would be a good thing, helping them cook through without turning leathery. In fact, I covered the pan with aluminum foil to trap the steam. After 15 minutes, the tip of a knife easily pierced the largest potato, so I removed the foil and continued to roast the fingerlings so the skins could take on some color, shaking the pan a few times to ensure that they browned evenly.
About 20 minutes later, I could see that this approach worked: Both the large and small spuds were tender and creamy. Most varieties of fingerlings are waxy, and waxy potatoes hold their moisture better than, say, floury russets, so it’s hard to dry them out. The extra steam from the larger potatoes also helped the smaller ones cook through.
To dress up my perfectly roasted fingerlings, I coated them with seasonings that would stick to their skin. For a simple yet classic combination, I tossed chopped thyme and sage leaves with the roasted potatoes in a bowl, where their heady fragrances wafted up as they hit the hot spuds.
But it was tricky to evenly disperse the small amount of herbs. For the next batch, I held off on adding salt prior to roasting the potatoes and instead added it to the herbs before I minced them. The increased volume made the ingredients easier to distribute evenly.
Two more potent toppings for my sophisticated, slender spuds included a zippy mix of lemon zest, garlic, and parsley and a salty-sharp take on cacio e pepe with Pecorino Romano and black pepper.