Adjust rack to top position and preheat oven to 425 degrees. Wash and dry produce.

Halve potatoes lengthwise. Roughly chop pistachios. Zest and quarter lemon. Zest orange, then remove peel from flesh; dice flesh into ½-inch pieces. Roughly chop parsley. Pick and roughly chop fronds from dill. 

Toss potatoes on one side of a baking sheet with a large drizzle of oil, half the garlic powder (you’ll use the rest later), half the Za’atar Spice, salt, and pepper. Roast on top rack for 12 minutes (you’ll add more to the sheet then).

Meanwhile, place 2 TBSP butter (3 TBSP for 4 servings) in a medium microwave-safe bowl. Microwave until melted, 30 seconds. Let cool slightly; stir in pistachios, panko, remaining Za’atar Spice, salt, and pepper.

Meanwhile, in a small bowl, combine lemon zest, half the sumac (you’ll use the rest in the next step), and remaining sour cream. Add water 1 tsp at a time until mixture reaches a drizzling consistency. Season with salt and pepper.

In a second medium bowl, whisk together juice from half the lemon, remaining garlic powder, remaining sumac, 1 TBSP olive oil, ½ tsp sugar, salt, and pepper (juice from whole lemon, 2 TBSP olive oil, and 1 tsp sugar for 4 servings).

Add coleslaw mix, diced orange, half the parsley, and half the dill. Toss to evenly coat; refrigerate until ready to serve.

Once potatoes are done, carefully transfer to a third medium bowl. Add a large drizzle of olive oil, feta, remaining parsley, and remaining dill; stir to combine.

Top sea bass with orange zest.

Divide sea bass, slaw (draining first), and feta potatoes between plates. Drizzle sumac sauce over fish. Serve with any remaining lemon wedges on the side.