Adjust racks to top and middle positions and preheat oven to 450 degrees. Wash and dry produce.

Cut potatoes into ½-inch-thick wedges. Halve, peel, and thinly slice half the shallot; finely dice remaining half. Trim and discard woody bottom ends from asparagus. Zest and quarter lemon.

Toss potatoes on a baking sheet with a drizzle of oil (large drizzle for 4 servings), salt, and pepper. Roast on top rack until browned and tender, 20-25 minutes.

While potatoes roast, heat a drizzle of oil in a large pan over medium-high heat. Add sliced shallot and a pinch of salt; cook, stirring, until browned and slightly softened, 1-2 minutes.

Stir in spinach; cook, stirring, until wilted, 2-4 minutes. Turn off heat; transfer to a medium bowl. Wipe out pan.

Add sour cream, half the cream cheese, and half the garlic powder (you’ll use the rest in Step 5) to same bowl; stir to combine. Season with salt and pepper.

Pat salmon* dry with paper towels. Place, skin sides down, on a clean work surface. Using a sharp knife, cut a slit lengthwise down the center of the flesh sides (be careful not to cut through the skin!). Rub all over with a drizzle of oil; season with salt and pepper. (Make sure to season inside the cuts too!)

Place salmon, skin sides down, on one side of a second lightly oiled baking sheet. Stuff salmon with spinach filling (it’s OK if they seem overstuffed).

Toss asparagus on opposite side of same sheet with a drizzle of oil (large drizzle for 4 servings), remaining garlic powder, salt, and pepper.

Roast on middle rack until salmon is cooked though and asparagus is tender, 12-15 minutes. TIP: If asparagus is done before salmon, remove from sheet and continue roasting salmon.

Meanwhile, heat a drizzle of oil in pan used for spinach over medium heat. Add diced shallot and a pinch of salt. Cook, stirring, until shallot is softened and translucent, 3-5 minutes.

Whisk in ¼ cup water (⅓ cup for 4 servings), stock concentrate, and remaining cream cheese. Cook, stirring, until thickened, 1-2 minutes.

Turn off heat. Stir in a pinch of lemon zest, juice from one lemon wedge (two wedges for 4), and 1 TBSP butter (2 TBSP for 4) until melted and combined. Season with salt and pepper.

Divide salmon, asparagus, and potatoes between plates. Spoon sauce over salmon. Serve with remaining lemon wedges on the side.