Add couscous and salt to taste in a small bowl; pour in 1 1/2 cup boiling water; cover and set aside.
To make the pesto: add the garlic, basil, olive oil, 1/4 teaspoon salt, and pepper to the container of a blender or food processor; blend or process until smooth.
Stir in cheese; set aside.
In a small, heavy, dry skillet over medium heat, toast walnuts for about 3-5 minutes, stirring constantly, until aromatic; watch closely to prevent burning; set aside.
To assemble wraps: Spread 2 tablespoons pesto, 1/2 cup couscous, 3/4 to 1 cup chicken, one-fourth of the walnuts, one-fourth of the sun-dried tomatoes,and one-fourth of the yellow bell pepper evenly over each tortilla--leave a 1-inch border.