Adjust racks to top and middle positions and preheat oven to 450 degrees. Wash and dry all produce. Halve, peel, and finely chop shallot. Strip rosemary leaves from stems; chop leaves until you have 2 tsp (4 tsp for 4 servings). Dice potatoes into 1/2-inch pieces.

Toss potatoes on a baking sheet with a drizzle of olive oil, half the chopped rosemary, and a pinch of salt and pepper. Roast on top rack, tossing halfway through, until tender and crisped, 20-25 minutes.

Meanwhile, pat pork dry with paper towels; season all over with salt and pepper. Heat a drizzle of olive oil in a large pan over medium heat. Add pork and sear, turning occasionally, until browned all over, 4-8 minutes. Transfer to a second baking sheet.

Toss green beans with a drizzle of olive oil and a pinch of salt and pepper on sheet with pork. Roast on middle rack until pork is cooked through and green beans are tender, 10-12 minutes. Let pork rest a few minutes after removing from oven, then thinly slice crosswise.

Heat a drizzle of olive oil in pan used for pork over medium heat. Add shallot and remaining chopped rosemary. Cook, stirring, until softened, 1-2 minutes. Stir in stock concentrate, vinegar, jam, and 1/4 cup water (1/2 cup for 4 servings). Simmer until thick and saucy, 2-3 minutes. Remove pan from heat and stir in 1 TBSP butter (2 TBSP for 4) until melted. Season with salt and pepper.

Divide potatoes, green beans, and pork between plates. Drizzle pan sauce over pork and serve.