Wash and dry all produce. Core and seed tomato, then cut into 1/2-inch pieces. Zest lemon until you have 1 tsp zest, then cut into wedges. Trim, then thinly slice scallions, keeping greens and whites separate. Mince or grate garlic.

In a small bowl, stir together sour cream, half the lemon zest, and a few squeezes of lemon juice (to taste— start with about 1/4 of the lemon and go up from there). Season with salt and pepper. Taste and add more lemon zest or juice, if desired.

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

Heat another 1 TBSP butter and a large drizzle of oil in pot used for couscous over medium-high heat. Once butter is melted, add scallion whites and tomato. Cook, stirring frequently, until slightly softened, 2-3 minutes. Lower heat to medium and add garlic. Cook until fragrant, about 1 minute. Stir in couscous. Season with salt and pepper, then remove pot from heat.

Heat a drizzle of oil in a medium pan over medium-high heat (use a nonstick pan if you have one). Pat salmon dry with a paper towel. Season all over with salt, pepper, and fry seasoning. Add to pan skin-side down. Cook until skin is crisp, 4-6 minutes. Flip and cook to desired doneness, 2-3 minutes more.

Fluff couscous with a fork, then stir in half the scallion greens. Divide between plates, along with salmon. (TIP: Arrange the fillets skin-side up to keep the skin crisp.) Drizzle salmon with a spoonful of crema. Sprinkle with remaining scallion greens. Serve with any remaining lemon wedges and crema on the side.