Pork Loin Recipe

Bring pork to room temperature

Remove the pork loin from the refrigerator 30–45 minutes before cooking so it comes closer to room temperature; pat dry with paper towels.

Preheat oven

Preheat the oven to 400°F (200°C). Position a rack in the middle of the oven.

Prepare herb-Dijon crust

In a small bowl combine Dijon mustard, olive oil, minced garlic, chopped rosemary, thyme and parsley, kosher salt and black pepper. Mix to form a spreadable paste.

Season pork

Place the pork loin on a cutting board. Trim any excessive fat if desired, leaving a thin fat cap for flavor. Brush the entire surface of the pork with the herb-Dijon paste, pressing the chopped herbs so they adhere.

Sear (optional but recommended)

Heat a large ovenproof skillet over medium-high heat with 1 tablespoon olive oil. When shimmering, add the pork loin and sear 2–3 minutes per side until a golden crust forms (use tongs to sear the edges as well). This step develops flavor and shortens oven time.

Roast

Transfer the skillet with pork to the preheated oven (or move the pork to a roasting pan if not using an ovenproof skillet). Roast at 400°F (200°C) until an instant-read thermometer inserted into the thickest part reads 140°F (60°C) for medium doneness (approximately 20–30 minutes for a 2 lb roast, but time varies by shape). Start checking temperature at 18 minutes.

Rest

Remove pork from oven and transfer to a cutting board. Tent loosely with foil and rest 10–15 minutes. Carryover cooking will raise internal temperature to about 145°F (63°C). Resting keeps meat juicy.

Prep onions

While the pork roasts, thinly slice the onions if not already sliced. Keep slices even for uniform cooking.

Cook onions low and slow

Heat a large skillet over medium heat and add butter and 1 tablespoon olive oil. When butter is melted and foaming, add the sliced onions, sprinkle with 1 teaspoon sugar and 1/2 teaspoon salt. Stir to coat and spread the onions out in an even layer.

Caramelize

Cook the onions gently, stirring every 4–6 minutes to prevent burning and promote even browning. After 20–30 minutes they will soften and begin to turn golden. Lower the heat if they brown too quickly. Continue cooking 30–40 minutes total until deep golden-brown and sweet. Toward the end, stir in balsamic vinegar and black pepper and cook 1–2 minutes more to deglaze and concentrate flavor.

Finish onions

Taste and adjust seasoning with salt and pepper. Keep warm until serving.

Deglaze pan

After removing the seared pork from the skillet or roasting pan, place the pan over medium heat on the stovetop. Add the white wine (or 1/2 cup stock) to deglaze, scraping up browned bits with a wooden spoon. Simmer until reduced by about half (2–3 minutes).

Make sauce

Add the remaining 1 cup stock and a thyme sprig. Bring to a gentle simmer and reduce until slightly thickened, about 5–7 minutes. Remove the thyme sprig and whisk in 1 teaspoon Dijon mustard. Off heat, swirl in the cold cubed butter one piece at a time to finish and give the sauce sheen. Season to taste with salt and pepper.

Combine with onions (optional)

For serving, you may stir half the caramelized onions into the pan sauce to meld flavors and spoon the rest over the sliced pork as a topping.

Slice the rested pork loin into 1/2-inch thick slices. Arrange on a platter, top with warm caramelized onions and drizzle with pan sauce. Garnish with a sprinkle of chopped parsley or thyme sprigs if desired. Serve immediately.