Wash and dry all produce. Trim and thinly slice scallions, keeping greens and whites separate. Halve tomato, then cut into 1/2-inch pieces.

Melt 1 TBSP butter in a medium pot over medium-high heat. Add couscous and cook, stirring occasionally, until lightly toasted, 2-3 minutes. Pour in 1 cup water and stock concentrate, then bring to a boil. Lower heat slightly and let simmer until al dente, 7-9 minutes. Cover pot and set aside.

Rinse salmon and pat dry with paper towel. Season all over with salt, pepper, and Italian seasoning. Heat 1 TBSP butter and 1 TBSP olive oil in a medium pan over medium-high heat (use a nonstick pan if you have one). Add salmon and cook skin-side down until crisp, 3-4 minutes. Flip and cook until opaque, about 3 minutes more.

Meanwhile, using a peeler, shave zucchini lengthwise into ribbons, rotating until you get to the seedy core; discard core. Zest lemon, then cut in half; cut one half into 2 wedges. Place scallion greens, tomato, and zucchini in a medium bowl. Add a large drizzle of olive oil and squeeze in juice from lemon half. Toss to combine and season with salt and pepper.

Fluff couscous with a fork, then stir in scallion whites and all but 1/4 tsp of the lemon zest. Season with salt and pepper. Divide couscous between bowls or plates.

Arrange salmon on top of couscous on plates. Spoon over veggies. In a small bowl, stir together reserved lemon zest, sour cream, salt, and pepper; add a splash or two of water as needed to give mixture a loose, drizzly consistency. Drizzle mixture over everything. Serve with lemon wedges for squeezing over.