Wash and dry produce.

Dice potatoes into ½-inch pieces.

Place potatoes in a medium pot with enough salted water to cover by 2 inches. Bring to a boil and cook until tender, 15-20 minutes. Reserve ½ cup potato cooking liquid, then drain. Return potatoes to pot; cover to keep warm.

While potatoes cook, trim and thinly slice mushrooms (skip if your mushrooms are pre-sliced!). Trim and thinly slice scallions, separating whites from greens.

Pat pork* dry with paper towels and season all over with salt and pepper.

Heat a drizzle of oil in a large pan over medium-high heat. Add pork and cook until browned and cooked through, 4-6 minutes per side.

Turn off heat; transfer to a cutting board and tent with foil to keep warm. Wipe out pan.

To pot with potatoes, add half the sour cream and ½ TBSP butter (1 TBSP for 4 servings); mash until smooth, adding splashes of reserved potato cooking liquid as needed.

Heat a drizzle of oil in pan used for pork over medium heat. Add mushrooms and scallion whites; cook, stirring occasionally, until browned and slightly crispy, 5-7 minutes. Season with salt and pepper.

Add vinegar, jam, remaining sour cream, and 1 tsp sugar (2 tsp for 4 servings); cook, stirring, until mushrooms are coated and sauce has thickened slightly, 1-2 minutes. TIP: If sauce seems too thick, stir in water 1 TBSP at a time.

Slice pork crosswise.

Divide pork and mashed potatoes between plates. Spoon mushroom sauce over pork and garnish with scallion greens. Serve.