Bring a medium pot of water to a boil over high heat. Rinse all produce. Finely chop parsley leaves, discarding stems. Finely chop capers and cornichons. Halve lemon. Trim and discard scallion root, then thinly slice. Mince garlic and, still on cutting board, sprinkle over ⅛ teaspoon salt. Using a large knife, carefully scrape over mixture at a 45° angle, pressing down repeatedly until a smooth paste forms.

Season boiling water generously with salt. Stir in couscous and cook until tender, about 8 minutes. Drain and return to pot, off heat.

While couscous cooks, in a medium bowl, stir together white wine vinegar, parsley, capers, cornichons, garlic paste, juice of ½ lemon, 2 tablespoons olive oil, ⅛ teaspoon salt, and pepper as desired to combine. Set aside until ready to serve.

Heat ½ tablespoon olive oil in a medium nonstick pan over medium heat. When the oil is shimmering, add spinach and peas and cook, stirring to wilt spinach, about 2 minutes. Transfer spinach and peas to pot with couscous, along with almonds, scallion, ¼ teaspoon salt, and pepper as desired and stir to combine. Set aside until ready to serve. Wipe pan from vegetables clean. Pat salmon dry with paper towel and season all over with ¼ teaspoon salt and pepper.

Return pan from vegetables to medium heat with 2 teaspoons olive oil. When the oil is shimmering, add salmon skin-side down and remaining lemon cut-side down. Sear together until salmon is golden on bottom, 5 minutes. Flip salmon and cover pan, keeping the lid slightly ajar for steam to escape. Continue searing until salmon is cooked through and opaque and lemon is charred, 3-5 minutes more.

Divide Israeli couscous between serving plates and top with salmon. Spoon over salsa verde. Squeeze charred lemon over salmon and dig in!