Adjust rack to top position (top and middle positions for 4 servings) and preheat oven to 450 degrees. Wash and dry produce.

Cut potatoes into ½-inch-thick wedges. Halve, peel, and cut onion into four wedges. Grate one wedge (two wedges for 4) on the largest holes of a box grater; cut remaining onion into ½-inch-thick wedges. Halve, core, and thinly slice bell pepper into ½-inch-thick strips.

Toss potatoes on a lightly oiled baking sheet with a large drizzle of olive oil, half the garlic powder, and a big pinch of salt and pepper.

Roast on top rack until browned and tender, 20-25 minutes (you’ll add more to the sheet after 5 minutes).

In a medium bowl, gently combine pork*, grated onion, oregano, panko, stock concentrate, half the feta (save the rest for serving), remaining garlic powder, ½ tsp salt (1 tsp for 4 servings), and pepper.

Form into two 1-inch-tall meatloaves (four loaves for 4).

Once potatoes have roasted 5 minutes, remove sheet from oven. Carefully add onion wedges and bell pepper to sheet; toss to combine. Season with a pinch of salt and pepper.

Push veggies to one side of sheet. Place meatloaves on empty side and return sheet to top rack. Roast until meatloaves are browned and cooked through and veggies are tender, 18-22 minutes. (For 4 servings, leave potatoes roasting. Toss bell pepper and onion on one side of a second sheet and place meatloaves on empty side; roast on middle rack.)

In a small microwave-safe bowl, combine vinaigrette and marinara. Microwave until warmed through, 30 seconds.

Divide roasted veggies and meatloaves between plates. Sprinkle veggies with remaining feta and drizzle meatloaves with as much tangy marinara as you like. Serve.