Adjust rack to top position (top and middle positions for 4 servings) and preheat oven to 425 degrees. Wash and dry produce.

Dice potatoes into ½-inch pieces. Finely chop pistachios (or crush in their bag with a heavy-bottomed pan or rolling pin). Trim and remove strings from snap peas. Zest and quarter lemon. Trim and thinly slice radishes into rounds. Roughly chop parsley. Pick and roughly chop fronds from dill.

Place potatoes in a small pot with enough salted water to cover by 2 inches. Bring to a boil, then reduce to a low simmer. Cook until tender, 15-20 minutes. Drain, then set aside.

While potatoes cook, in a small bowl, combine pistachios, panko, half the garlic powder (you'll use the rest later), 1 tsp herbes de Provence (be sure to measure; we sent more), 1 tsp olive oil, and a pinch of salt and pepper (2 tsp herbes de Provence and 2 tsp olive oil for 4 servings).

Pat tilapia* dry with paper towels; season all over with salt and pepper. Place on one side of a lightly oiled baking sheet (spread out across entire sheet for 4 servings).

Evenly spread sour cream onto tops of fish. Mound with panko mixture, pressing to adhere (no need to coat undersides!).

Toss snap peas on opposite side of sheet from tilapia with 1 tsp olive oil (2 tsp for 4 servings), salt, and pepper. (For 4, toss snap peas on a second baking sheet.)

Roast on top rack until tilapia is golden and cooked through and snap peas are tender, 8-10 minutes. (For 4, roast tilapia on top rack and snap peas on middle rack.)

Meanwhile, in a large bowl, combine lemon zest, remaining garlic powder, 2 TBSP olive oil, 2 tsp vinegar, 1 tsp mustard, juice from half the lemon, salt, and pepper (4 TBSP olive oil, 4 tsp vinegar, and 2 tsp mustard for 4 servings). (Be sure to measure the vinegar and mustard—we sent more!)

Add potatoes, snap peas, radishes, parsley, and dill to bowl with dressing; toss until everything is evenly combined.

Divide salad between bowls and top with tilapia; serve with remaining lemon wedges on the side.