This recipe is a modernized version of Hannah Glasse’s recipe for Roast Pork Loin in her cookbook, The Art of Cookery Made Plain and Easy, published in England in 1747.

“To dress a Loin of Pork with onions Take a Fore-Loin of Pork and roast it, as at another time, peel a Quarter of a Peck of Onions, and slice them thin, lay them in the Dripping pan, which must be very clean, under the Pork, let the Fat drop on them; when the Pork is nigh enough, put the Onions into the sauce-pan, let them simmer over the Fire a Quarter of an Hour, shaking them well, then pour out all the Fat as well as you can, shake in a very little Flour, a Spoonful of Vinegar, and three Tea Spoonfuls of Mustard, shake all well together and stir in the Mustard, set it over the Fire for four five Minutes, lay the Pork in a Dish and the Onions in a Bason. This is an admirable Dish to those who love Onions.”

1 ½ pound pork tenderloin
salt and pepper
1 teaspoon flour, plus more for dusting
2 tablespoons butter
1 tablespoon olive oil
1 onion, thinly sliced
3 garlic cloves, smashed
¼ cup dry white wine
½ cup chicken broth
3 tablespoons whole grain mustard
1 tablespoon apple cider vinegar, or to taste
1 tablespoon chopped fresh dill

Preheat oven to 350°F with rack in middle. Pat pork dry, season with salt and pepper and dust with flour.

Heat butter and oil in a 12-inch ovenproof heavy skillet over medium-high heat. Brown pork on all sides, about 6 minutes total, then transfer to a plate.

Sauté thinly sliced onion and garlic in the same skillet until the onion starts to caramelize. Add wine, stirring and scraping up brown bits, then stir in broth and mustard. Place pork over the onions and transfer skillet to oven.

Roast until an instant-read thermometer inserted into center of pork registers 145° to 150° F, about 20 minutes.

Transfer pork to a cutting board and let rest 10 minutes before slicing. Transfer the skillet to stovetop and bring to a boil and stir in the vinegar and dill.

Thinly slice the pork and pour the onions and mustard sauce over it.

Serves 6