Wash and dry produce.

Dice potatoes into ½-inch pieces.

Place potatoes in a medium pot with enough salted water to cover by 2 inches. Bring to a boil and cook until tender, 15-18 minutes. Drain.

While potatoes cook, zest and quarter lemon. Trim and thinly slice scallions. Roughly chop olives. Halve, peel, and finely dice shallot.

Place 1 TBSP butter (2 TBSP for 4 servings) in a small microwave-safe bowl. Microwave until just softened, 5-10 seconds (repeat in 5-second increments if necessary).

Stir in sun-dried tomato paste until well combined. Season with salt and pepper.

In a medium bowl, whisk together lemon zest, mustard, 1 TBSP olive oil (2 TBSP for 4 servings), juice from half the lemon, salt, and pepper.

Add drained potatoes, scallions, olives, and shallot; toss until everything is evenly coated.

Pat barramundi* dry with paper towels; season all over with salt and pepper.

Heat a large drizzle of olive oil in a large, preferably nonstick, pan over medium-high heat. Add barramundi to pan, skin sides down. Cook until skin is crispy, 3-4 minutes.

Flip and continue to cook until barramundi is cooked through, 2-3 minutes more.

Turn off heat; transfer to a plate.

Divide potato salad between plates and top with barramundi. Dollop sun-dried tomato butter over barramundi. Serve with remaining lemon wedges on the side.