1
Adjust rack to top position and preheat oven to 450 degrees. Bring a large pot of salted water to a boil. Wash and dry produce.
Halve, core, and thinly slice bell pepper. Trim and halve zucchini lengthwise; slice crosswise into ½-inch-thick half-moons. Trim and thinly slice scallions, separating whites from greens. Zest and quarter lemon.