Preheat the oven to 450°F. Wash and dry the fresh produce. Line two sheet pans with foil. Halve and peel the onion(s); cut into 1-inch-wide wedges, separating the layers. Medium dice the potatoes. Cut off and discard the stem of the pepper(s). Halve lengthwise; remove the ribs and seeds, then cut crosswise into 1-inch pieces. Transfer to one sheet pan. Drizzle with olive oil and season with salt, pepper, and half the spice blend; toss to coat. Arrange in an even layer. Roast 22 to 26 minutes, or until browned and tender when pierced with a fork. Remove from the oven.

Meanwhile, quarter and deseed the lemon(s). In a bowl, combine the chimmichurri sauce, mayonnaise, and the juice of 2 lemon wedges (or 4 wedges for 4 servings). Season with salt and pepper.

Once the vegetables have roasted about 10 minutes, lightly coat the center of the remaining sheet pan with a drizzle of olive oil. Pat the fish dry with paper towels. Season on both sides with salt, pepper, and the remaining spice blend. Transfer to the oiled portion of the sheet pan, skin side down. Roast 10 to 15 minutes, or until browned and cooked through. Remove from the oven.

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

Evenly top the roasted vegetables with the juice of the remaining lemon wedges. Toss to coat. Serve the roasted fish with the finished vegetables. Serve the chimichurri mayo on the side. Enjoy!