Adjust rack to upper position and preheat oven to 450 degrees. Wash and dry all produce. Halve and peel shallot. Finely mince one half and thinly slice the other.

Melt half the garlic herb butter in a medium pot over medium-high heat. Add minced shallot. Cook, stirring, until just softened, 2-3 minutes. Stir in 3/4 cup water (11/2 cups for 4 servings), half the stock concentrate, and a pinch of salt. Bring to a boil. Stir in couscous, then remove from heat and cover. Keep covered until ready to serve.

Toss broccoli on a baking sheet with a drizzle of oil and a pinch of salt and pepper. Roast until browned and tender, 10-15 minutes.

Meanwhile, pat pork dry with paper towels; season all over with salt and pepper. Heat a drizzle of oil in a large pan over medium-high heat. Working in batches if necessary, add pork and cook until browned and cooked through, 2-3 minutes per side. Turn off heat; remove pork from pan and set aside, covered.

Heat another drizzle of oil in same pan over medium heat. Add sliced shallot and cook, stirring, until lightly browned, 4-5 minutes. Pour in vinegar and simmer until slightly reduced, about 1 minute. Stir in jam, 1/3 cup water (1/2 cup for 4 servings), and remaining stock concentrate. Simmer until thickened, 3-5 minutes. Season with salt, pepper, and 1/4 tsp sugar (1/2 tsp for 4 servings). Turn off heat. Add 1 TBSP plain butter (2 TBSP for 4 servings) and stir until melted. Return pork to pan; flip to coat in sauce.

Fluff couscous with a fork; stir in remaining garlic herb butter. Divide couscous, broccoli, and pork between plates. Top pork with any remaining sauce.