Place the eggs in a single layer in a large saucepan and cover with cold water by about 1–2 inches. Bring to a gentle boil over medium-high heat, then cover, turn off the heat, and let sit for 10–12 minutes for firm, bright yolks.

While the eggs sit, fill a large bowl with ice and cold water. When the time is up, transfer the eggs to the ice bath and let sit for at least 10 minutes to stop the cooking and make peeling easier.

Gently tap each egg on the counter to crack the shell, then roll lightly to loosen it. Peel under cool running water if needed to get under the membrane.

Pat the peeled eggs dry and slice in half lengthwise with a sharp knife, wiping the blade between cuts for clean edges. Carefully pop the yolks into a mixing bowl and arrange the egg white halves on a serving tray.

Using a fork, mash the yolks until very fine and crumbly with no large chunks; this helps create a smooth, silky filling.

To the mashed yolks, add the mayonnaise, sour cream or Greek yogurt, Dijon mustard, lemon juice, garlic powder, onion powder, salt, and pepper. Stir until smooth and well combined. If too thick, add a tiny splash of water or more mayo, about 1 teaspoon at a time.

Stir in 1 teaspoon of truffle oil and the chopped chives. Taste and add up to an additional 1/2 teaspoon truffle oil, a few drops at a time, until the truffle flavor is pleasantly aromatic but not overpowering.

Taste the filling and adjust with more salt, pepper, or lemon juice as needed. Aim for a flavor that is slightly bolder than you want in the finished eggs, as it will mellow once chilled.

Transfer the filling to a piping bag fitted with a star tip (or a zip-top bag with a small corner snipped off) and pipe into each egg white half. Alternatively, spoon the filling in and swirl with the back of a teaspoon.

Cover the tray loosely with plastic wrap and chill the deviled eggs for 30–45 minutes to allow the flavors to meld and the filling to firm slightly.

Just before serving, garnish with extra chopped chives, a sprinkle of flaky sea salt, and freshly cracked black pepper. Add a light dusting of smoked paprika or additional pepper for color, and, if desired, a small shaving of truffle or pinch of truffle salt on some eggs.