Adjust rack to top position and preheat oven to 425 degrees. Wash and dry all produce. Cut potatoes into 1/2-inch-thick wedges. Halve, peel, and finely dice onion. Thinly slice tomato into rounds. Thinly slice pickle into rounds; mince a few slices until you have 2 TBSP (4 TBSP for 4 servings). Tear off a few romaine leaves for topping your burgers (save the rest for another use). Halve buns.

Toss potatoes on a baking sheet with a large drizzle of oil, Fry Seasoning, salt, and pepper. Roast on top rack until browned and crispy, 20-25 minutes.

Meanwhile, in a small bowl, combine sour cream, ketchup, mustard, minced pickle, 1 tsp sugar (2 tsp for 4 servings), and 1/4 tsp garlic powder (1/2 tsp for 4; we sent more).

Heat a drizzle of oil in a large pan over medium-high heat. Add onion and cook, stirring occasionally, until browned and softened, 5-7 minutes. Season with salt and pepper. Transfer to a second small bowl.

Season patties all over with salt and pepper. Heat a drizzle of oil in pan used for onion over medium-high heat. Add patties and cook until browned, 3-5 minutes per side. Top each patty with cheddar. Reduce heat to medium; cover pan until cheese is melted, 1-2 minutes.

Meanwhile, toast buns until golden brown. Fill toasted buns with patties, romaine leaves, tomato, sliced pickle, cooked onion, and sauce. Serve potato wedges on the side with any remaining sauce for dipping.