Meanwhile, lightly coat the center of a separate sheet pan with oil. In a bowl, combine the pesto and mayonnaise. Place 2/3 of the pesto mayo in a separate bowl; set aside for serving. Pat the fish dry with paper towels; season with salt and pepper on both sides. Transfer the seasoned fish to the oiled portion of the sheet pan, skin side down. Evenly top with the remaining pesto mayo and breadcrumbs (pressing gently to adhere). Drizzle with olive oil.  

Roast the coated fish 10 to 15 minutes, or until the breadcrumbs are lightly browned and the fish is cooked through.* Remove from the oven.   

*The USDA recommends a minimum safe cooking temperature of 145°F for fish.

Preheat the oven to 450°F. Wash and dry the fresh produce. Halve the radishes lengthwise. Halve and peel the onion; cut into 1-inch-wide wedges, separating the layers. Medium dice the potatoes. Transfer to a sheet pan. Drizzle with olive oil and season with salt, pepper, and the spice blend; toss to coat. Arrange in an even layer. Roast 24 to 26 minutes, or until browned and tender when pierced with a fork. Remove from the oven.

Meanwhile, halve the lemon crosswise; remove the seeds. To the bowl of reserved pesto mayo, add the juice of 1 lemon half; stir to combine. Taste, then season with salt and pepper if desired. Evenly top the roasted vegetables with the juice of the remaining lemon half. Serve the roasted fish with the finished vegetables. Serve the lemon pesto mayo on the side. Enjoy!