Adjust rack to top position and preheat oven to 450 degrees. Wash and dry produce.

Cut potatoes into ½-inch-thick wedges. Trim and thinly slice mushrooms (skip if your mushrooms are pre-sliced!). Halve buns.

Toss potatoes on a baking sheet with a large drizzle of olive oil and a big pinch of salt and pepper.

Roast on top rack until browned and crisp, 20-25 minutes.

Meanwhile, melt 1 TBSP butter (2 TBSP for 4 servings) in a large pan over medium-high heat. Add mushrooms and cook, stirring, until lightly browned and softened, 3-5 minutes. Season with salt and pepper.

Stir in half the stock concentrate (you’ll use the rest in the next step) and 1 TBSP water (2 TBSP for 4). Cook, stirring, until mushrooms are coated, 30 seconds.

Turn off heat; transfer to a small bowl. Wipe out pan.

In a large bowl, combine beef* and remaining stock concentrate. (TIP: Not sure how much beef to use? Refer to the “Before you start” section at left for guidance.) Season with salt (we used ½ tsp; 1 tsp for 4 servings) and pepper. Form mixture into two patties (four patties for 4), each slightly wider than a burger bun.

Heat a large drizzle of olive oil in pan used for mushrooms over medium-high heat. Add patties; cook until browned and cooked through, 3-5 minutes per side.

In the last 1-2 minutes of cooking, top each patty with Swiss cheese. Cover pan until cheese melts.

While patties cook, toast buns until golden.

In a second small bowl, combine sour cream and honey Dijon dressing. Season with salt and pepper.

Spread bottom buns with as much sauce as you like. Top with patties, mushrooms, and top buns.

Divide burgers and potato wedges between plates. Serve with any remaining sauce on the side for dipping.