Adjust rack to top position and preheat oven to 425 degrees. Wash and dry produce.

Peel and dice potatoes into ½-inch pieces. Halve, peel, and mince shallot.

Place potatoes in a large pot with enough salted water to cover by 2 inches.

Bring to a boil and cook until tender, 15-20 minutes. Reserve ½ cup potato cooking liquid (1 cup for 4 servings), then drain and return potatoes to pot.

Add 3 TBSP butter (6 TBSP for 4). Mash with a potato masher or fork until smooth, adding splashes of reserved potato cooking liquid as needed. Season with salt and pepper.

Keep covered off heat until ready to serve.

While potatoes cook, place bratwurst* on a baking sheet. Roast on top rack until browned and cooked through, 10-15 minutes.

Heat a drizzle of oil in a large pan over medium-high heat. Add shallot and cook, stirring occasionally, until lightly browned, 1-2 minutes.

Stir in stock concentrate and ¼ cup water (½ cup for 4 servings). Cook until slightly reduced, 1-2 minutes. Add sour cream, mustard, garlic powder, and half the Worcestershire sauce (all for 4); stir to combine.

Turn off heat; stir in 1 TBSP butter (2 TBSP for 4). Season with salt and pepper.

In a large bowl, whisk together half the vinegar, ½ tsp sugar, a drizzle of olive oil, salt, and pepper (all the vinegar, 1 tsp sugar, and a large drizzle of olive oil for 4 servings).

Add mixed greens to bowl with dressing; toss to combine.

Slice bratwurst on a diagonal into ½-inch-thick pieces. TIP: Use tongs or a fork to hold bratwurst in place for slicing if too hot to handle.

Divide mashed potatoes and salad between plates. Top potatoes with sliced bratwurst; spoon sauce over top and serve.