Wash and dry all produce. Trim and thinly slice scallions, separating whites from greens. Dice tomato.

Melt 1 TBSP butter (2 TBSP for 4 servings) in a medium pot over mediumhigh heat. Add couscous and cook, stirring occasionally, until lightly toasted, 2-3 minutes. Pour in ¾ cup water (1½ cups for 4) and stock concentrate. Bring to a boil, then cover and reduce heat to low. Cook until al dente, 6-8 minutes. Pour out any excess liquid, if necessary. Cover pot and set aside.

Rinse salmon, then pat dry with paper towels. Season all over with salt, pepper, and Italian Seasoning. Heat 1 TBSP butter and 1 TBSP olive oil in a large, preferably nonstick, pan over medium-high heat. Add salmon and cook, skin sides down, until browned and crispy, 3-4 minutes. Flip and cook until firm and opaque, 3-4 minutes more. Transfer to a paper-towel-lined plate.

Meanwhile, using a peeler, shave zucchini lengthwise into ribbons, rotating as you go, until you get to the seedy core; discard core. Zest and halve lemon; cut one half into two wedges (for 4 servings, halve one lemon and quarter other). In a medium bowl, combine scallion greens, tomato, and zucchini ribbons. Add a large drizzle of olive oil and juice from lemon half (two halves for 4). Season with salt and pepper and toss to combine.

Reserve ¼ tsp lemon zest (½ tsp for 4 servings). Fluff couscous with a fork, then stir in scallion whites and remaining lemon zest. Season with salt and pepper. In a small bowl, combine sour cream, reserved lemon zest, salt, and pepper. Add water, 1 tsp at a time, until mixture reaches a drizzling consistency.

Divide couscous between bowls or plates; top with salmon and veggies. Drizzle crema over everything. Serve with lemon wedges on the side.