Wash and dry all produce. Adjust oven racks to middle and top position. Preheat oven to 450 degrees. Cut potatoes into 1/2-inch-thick wedges (like steak fries). Toss on a baking sheet with fry seasoning and 4 tsp oil. Season with salt and pepper.

Roast potatoes in oven on middle rack until browned and crisp, about 25 minutes, tossing halfway through. On another baking sheet, toss broccoli, a large drizzle of oil, and a pinch of salt and pepper. Roast in oven on top rack until tender and crisp, about 15 minutes.

Finely chop dill until you have 1 TBSP. Cut cucumbers lengthwise into thin spears. Mince a spear or two until you have 3 TBSP minced cucumber and set aside in a small bowl.

Add mayonnaise and half the dill to bowl with minced cucumber and stir to combine. Season to taste with salt, pepper, and up to 2 tsp vinegar. Set aside 4 tsp sauce for brushing fish. In a medium bowl, toss together cucumber spears, remaining vinegar, and 1 tsp sugar. Season with salt and pepper

Microwave 2 TBSP butter to melt in another small bowl on high heat, about 20 seconds. (TIP: Alternatively, melt butter in a small pan over medium heat.) Stir in panko and remaining dill. Season with salt and pepper. Once broccoli is done, remove from baking sheet and set aside. Pat catfish dry with a paper towel, then place on same baking sheet.

Brush 1 tsp of reserved sauce onto top of each catfish fillet. Press panko mixture into sauce to adhere. Bake in oven until just opaque, about 5 minutes. Heat broiler to high, then transfer sheet to broiler. Broil until crust is golden brown, 2-3 minutes. Divide between plates and serve with broccoli, potatoes, pickles, and sauce to the side.