Step 1

• Adjust rack to top position and preheat oven to 425 degrees. Wash and dry produce. • Cut potatoes into ½-inch-thick wedges. Halve, peel, and thinly slice onion.

Step 2

• Toss potatoes on a baking sheet with a drizzle of oil and half the Old Bay Seasoning (you’ll use more later). Season lightly with salt and pepper. TIP: No need to season generously— there’s already salt and pepper in the seasoning! • Roast on top rack until browned and crispy, 20-25 minutes.

Step 3

• While potatoes roast, heat a large drizzle of oil in a medium, preferably nonstick, pan over medium-high heat. Add onion; cook, stirring occasionally, until browned and softened, 8-10 minutes. • Add 1 tsp sugar (2 tsp for 4 servings) and a splash of water; cook until onion is caramelized and jammy, 2-3 minutes more. Season with salt and pepper. • Turn off heat; transfer to a small bowl.

Step 4

• Meanwhile, in a second small bowl, combine mayonnaise, ketchup, mustard, and as much remaining Old Bay Seasoning as you like. Set aside. • Form beef* into two equal-size balls (four balls for 4 servings); season all over with salt and pepper.

Step 5

• Heat a drizzle of oil in pan used for onion over medium-high heat. Once pan is hot, add beef. Firmly flatten each ball with a spatula to create very thin patties. (TIP: Do so carefully; oil may splatter a bit.) Cook to desired doneness, 3-4 minutes per side. (Don’t worry if the patties aren’t perfectly round—those irregular edges will turn crispy.) • In the last 1-2 minutes of cooking, top patties with cheddar; cover pan until cheese melts. Remove from heat.

Step 6

• While patties cook, halve and toast buns. • Divide buns between plates and fill with patties, caramelized onion, and half the special sauce. Serve Old Bay fries on the side with remaining special sauce for dipping.