Adjust rack to top position (top and middle positions for 4 servings) and preheat oven to 425 degrees. Wash and dry produce.

Cut potatoes into ¼-inch-thick rounds. Peel and mince or grate garlic. Trim and halve Brussels sprouts lengthwise. Halve, peel, and mince shallot. Pick and finely chop fronds from dill. Zest and quarter lemon.

In a large bowl, toss potatoes with 2 TBSP oil (4 TBSP for 4 servings), garlic, and a couple big pinches of salt and pepper until thoroughly coated.

Arrange potatoes on one side of a baking sheet in a single overlapping layer (for 4, layer potatoes across entire sheet). TIP: Be sure to shingle the potatoes in a single layer so they cook evenly.

Roast on top rack for 5 minutes (you’ll add the Brussels sprouts then).

Once potatoes have roasted 5 minutes, remove sheet from oven. Carefully add Brussels sprouts to empty side; toss with a drizzle of olive oil, salt, and pepper. (For 4 servings, leave potatoes roasting; add Brussels sprouts to a second baking sheet and roast on middle rack.)

Return sheet to top rack and roast until Brussels sprouts and potatoes are browned and tender, 15-18 minutes more.

While Brussels sprouts and potatoes roast, pat trout* dry with paper towels and season all over with salt and pepper.

Heat a drizzle of oil in a large pan over medium heat. Add trout, skin sides down, to hot pan. Cook until skin is crispy, 5-6 minutes.

Flip trout; continue cooking until opaque and cooked through, 4-6 minutes more. Turn off heat; transfer to a plate. Wipe out pan.

Heat a drizzle of oil in same pan over medium-high heat. Add shallot; cook, stirring, until slightly softened, 2-3 minutes.

Stir in mustard, stock concentrate, honey, and ¼ cup water (⅓ cup for 4 servings). Simmer until slightly thickened, 2-3 minutes. Turn off heat.

Stir in sour cream, half the chopped dill, juice from one lemon wedge, and 1 TBSP butter until melted and combined. (For 4, use all the chopped dill, juice from two lemon wedges, and 2 TBSP butter.) Season with salt and pepper.

Carefully toss Brussels sprouts with a pinch of lemon zest to taste.

Divide potatoes, Brussels sprouts, and trout between plates. Spoon half the sauce over trout. Serve with remaining sauce and any remaining lemon wedges on the side.