Adjust rack to top position and preheat oven to 425 degrees. Wash and dry all produce. Cut potatoes into ½-inch-thick wedges. Trim and thinly slice scallions, separating whites from greens. Zest and halve lemon (halve both lemons for 4 servings).

Toss potatoes on a baking sheet with a large drizzle of olive oil, half the paprika, half the garlic powder (you’ll use the rest of each spice later), salt, and pepper. Roast on top rack until browned and tender, 20-25 minutes.

Meanwhile, in a medium bowl, combine mayonnaise, sour cream, juice from half the lemon (whole lemon for 4 servings), half the celery salt (you’ll use the rest later), and 1½ tsp sugar (3 tsp for 4). Add coleslaw and scallion greens; toss to coat. Season generously with salt and pepper. Set aside to marinate.

Place 1 TBSP butter (2 TBSP for 4 servings) in a small microwave-safe bowl; microwave until melted, 30 seconds. Slice baguettes lengthwise, stopping before you get all the way through. (Alternatively, halve buns lengthwise.) Spread melted butter onto cut sides of buns; toast until golden brown.

While buns toast, rinse shrimp under cold water; pat dry with paper towels. Toss in a second medium bowl with a large drizzle of olive oil, a large pinch of salt and pepper, and remaining paprika, garlic powder, and celery salt. Heat a large drizzle of olive oil in a large pan over medium-high heat. Once hot, add shrimp and scallion whites. Cook, stirring occasionally, until shrimp is pink and cooked through, 3-4 minutes. Turn off heat. Stir in 1 TBSP butter (2 TBSP for 4 servings) and lemon zest to taste.

Fill toasted buns with shrimp. Top with as much slaw as you like. Drizzle with hot sauce if desired. Divide between plates with potato wedges. Slice remaining lemon into wedges and serve on the side. TIP: If you’ve got some, serve with ketchup for dipping.