Thanks to two quick-cooking ingredients—couscous and shrimp—this tasty skillet supper comes together in no time at all. Remove the pan from the stovetop right after the shrimp turn pink. They’ll finish cooking in the hot skillet without turning rubbery.
Combine shrimp, garlic, black pepper, 3 tablespoons of the olive oil, 1 tablespoon of the lemon juice, and 1⁄2 teaspoon of the salt in a medium bowl; toss to coat. Let stand at room temperature until ready to use.
Heat 1 tablespoon of the olive oil in a 10-inch cast-iron skillet over medium-high. Add bell peppers; cook, stirring occasionally, until tender-crisp and charred, about 5 minutes. Sprinkle with 1⁄4 teaspoon of the salt. Transfer to a plate.
Add couscous to skillet; cook over medium-high, stirring constantly, until toasted and fragrant, about 2 minutes. Add stock and remaining 1⁄2 teaspoon salt; bring to a boil. Cover and reduce heat to medium-low; simmer until tender and almost all liquid is absorbed, about 10 minutes.
Uncover skillet, and top couscous with bell peppers and shrimp. Increase heat to medium; cover and cook until shrimp are just cooked through, 5 to 7 minutes. Remove from heat, and drizzle with remaining 2 tablespoons each olive oil and lemon juice. Garnish with parsley, basil, and crushed red pepper. Serve with lemon wedges.