Add potatoes to a large bowl. Drizzle with 2 tablespoons Italian dressing and season with salt and pepper; toss to coat. Arrange potatoes cut-side down on a rimmed baking sheet and roast until potatoes are tender, 20-25 minutes.
While the potatoes roast, trim green beans and place in the same large bowl used for the potatoes. Drizzle with 2 tablespoons Italian dressing and season with salt and pepper; toss to coat.
When potatoes are tender, remove from oven and preheat broiler to high.
Arrange salmon in center of baking sheet with potatoes and add green beans. Drizzle remaining tablespoon Italian dressing over the salmon and season with salt and pepper. Squeeze lemon halves over entire baking sheet and, if desired, slice lemon slices and add to baking sheet.
Broil salmon, green beans, potatoes, and lemons 10 minutes, or until salmon is no longer translucent but still moist in center and green beans, potatoes, and lemons are lightly browned. Serve with tartar sauce, if desired.
If your potatoes are browning too quickly under the broiler, tent them with some tin foil.
Feel free to use fat-free Italian dressing in this recipe too for a healthier option.
Swap out the green beans or potatoes for your favorite vegetable. The options are endless!