Place 2 1/2 cups or 2 (10.5-ounce) cans chicken or turkey gravy and 1/2 cup sour cream in a large bowl and whisk until smooth. Add the vegetables and 4 cups cooked, shredded chicken or turkey (about 1 pound). Stir until everything is evenly coated with sauce. Taste and season with kosher salt and black pepper as needed.