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 and finely chop enough rosemary leaves from stems to give you 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 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 same 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 cut into thin slices.

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

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