Step 1

Adjust rack to top position (top and middle positions for 4 servings) and preheat oven to 450 degrees. Wash and dry all produce. Cut potatoes into ½-inch-thick wedges. Trim and halve zucchini lengthwise; cut crosswise into ½-inch-thick half-moons. Mince chives. Zest and quarter lemon (for 4, zest 1 lemon; quarter both).

Step 2

Toss potatoes on one side of a baking sheet with a large drizzle of olive oil, salt, and pepper. (For 4 servings, spread out across entire sheet.) Roast on top rack for 10 minutes (you’ll add the zucchini then).

Step 3

Meanwhile, in a large bowl, toss zucchini with a drizzle of olive oil and a pinch of salt and pepper. Once potatoes have roasted 10 minutes, remove sheet from oven; add zucchini to empty side. (For 4, leave potatoes roasting and add zucchini to a second sheet; roast on middle rack.) Return to oven until potatoes are golden brown and zucchini is lightly browned, 12-15 minutes more. Once zucchini is done, remove from oven; toss with lemon zest.

Step 4

Pat salmon dry with paper towels; season all over with salt and pepper. Heat 1 TBSP butter and 1 TBSP olive oil in a large pan over medium-high heat. Add salmon skin sides down and cook until skin is crisp and fish is almost cooked through, 5-7 minutes. Flip and cook until fish is cooked through, 1-2 minutes more. Remove from pan and set aside. Wipe out pan.

Step 5

Return same pan to medium-high heat. Add stock concentrate, half the mustard (all for 4 servings), juice from half the lemon, and ¼ cup water (⅓ cup for 4). Simmer until slightly thickened, 2-3 minutes. Turn off heat. Stir in sour cream, half the chives, and 1 TBSP butter (2 TBSP for 4). (TIP: If sauce seems too thick, add water 1 tsp at a time until it reaches a drizzling consistency.) Season with salt and pepper.

Step 6

Divide salmon, potatoes, and zucchini between plates. Drizzle sauce over salmon. Garnish with remaining chives if desired. Serve with remaining lemon wedges on the side.