Pork

Adjust oven racks to top and middle and preheat oven to 450°F. Dice potatoes into 1/2-inch pieces, toss with a drizzle of oil, salt, and pepper on a baking sheet, and roast on the top rack 12 minutes.
Halve and core the apple and thinly slice; peel and finely chop the garlic; quarter the lemon. Trim zucchini, halve lengthwise and cut into 1/2-inch half-moons, toss zucchini with a drizzle of oil and a pinch of salt and pepper on a second baking sheet, and set aside.
Pat pork dry and season 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, 4–5 minutes per side; transfer to a plate.
Transfer the baking sheet with zucchini to the middle rack and continue roasting until both potatoes and zucchini are browned and softened, 12–15 minutes more.
Melt 1 TBSP butter in the pan used for pork over medium-high heat, add apple and cook until slightly softened, 2–3 minutes; add garlic and cook 30 seconds. Add water, chicken stock, and sugar, and cook, stirring, until the sauce thickens and the apple is very tender, 3–5 minutes; season to taste.
Remove the pan from heat and stir in 1 TBSP butter and a squeeze of lemon juice. Divide pork, zucchini, and potatoes between plates, top pork with the glazed apple sauce, and top zucchini with a squeeze of lemon.