Preheat oven to 375 degrees F.: When you step into the kitchen you should already sense warmth building, a steady dry heat that will coax sugars in the vegetables to caramelize and firm the proteins in the salmon . The oven at 375 degrees F offers a balance between a gentle roast and a quick finish, producing flaky fish without drying it out. You will notice the oven light glow and the metal rack feel evenly warm when you place your hand near the closed door, but do not touch it. A common mistake is rushing the preheat, which leads to uneven cooking and underdone centers, so give the oven those full minutes to stabilize.
In a small bowl combine olive oil, salt, pepper, and lemon zest.: As you whisk those elements together, the aroma of the lemon zest will become prominent, releasing bright citrus oils that cling to the oil. This mixture is the seasoning glue, and its glossy texture helps the spices coat the vegetables and the salmon uniformly. If the oil separates slightly, that is fine, just stir again; the goal is an even distribution of flavor. Avoid over-salting at this stage, many cooks add too much and the final dish becomes flat.
Place salmon and vegetables on a rimmed sheet pan.: Lay out the pieces with space between them so air can circulate, and the hot oven can create those desirable roasted edges. The visual cue you want is roominess, not crowded lumps. For the salmon , place skin side down if it has skin, and give each portion its own space so the heat envelops it. A frequent misstep is overcrowding the pan, which causes steaming instead of roasting; keep some gaps between items to encourage browning.
Rub salmon and vegetables with seasoning mixture and distribute evenly on sheet pan.: As you rub, you will feel the oil slick the surfaces and the zest cling to the flesh and florets. Massage the seasoning gently into the salmon so it adheres, and toss the vegetables so each piece is coated. Visually, you should see a sheen on everything and tiny flecks of zest across the surfaces. If some pieces look dry, apply a touch more oil; undercoating leads to uneven caramelization, so be generous enough to encourage browning but not so much the pan pools with fat.
Roast uncovered in oven for 15-20 minutes, until vegetables are tender-crisp, and salmon is cooked through.: As the tray roasts you will hear a soft whisper of moisture escaping and see the vegetables begin to blister and deepen in color, the broccoli tips may turn a toasted brown and the asparagus edges will show caramelized marks. The salmon will firm up and flake when touched gently with a fork; look for opaque flesh that flakes easily. The timing window of 15 to 20 minutes depends on piece thickness, and if your salmon is thicker it may need a few extra minutes. Avoid overcooking, which dries the fish; if unsure, check a small area at the lower end of the timing to prevent a too-firm texture.
Sprinkle with feta cheese crumbles and serve.: After removing the pan from the oven, the scent will be a layered chorus of roasted greens, citrus brightness, and warm, rich salmon . Scatter the crumbly feta so it lands on warm surfaces and softens without fully melting, adding immediate contrast. Serve straight from the pan or transfer to a platter, and notice how the textures and flavors mingle on the plate. A misstep here is adding the feta too early in the roast, which makes it weep or burn; add it at the finish for the best textural pop.