One Skillet Cajun Shrimp and Rice

Name: One-Skillet Cajun Shrimp and Rice
Ingredients: 1 cup brown rice; 1 pound shrimp, deveined; 3 teaspoons Cajun seasoning; Kosher salt and freshly ground black pepper; 1 tablespoon olive oil, plus more as needed; 2 celery ribs, finely sliced; 1 green bell pepper, diced; 2 links andouille sausage, sliced 1/4 inch thick; 1/2 cup chicken broth; 1/2 cup milk; 1 tablespoon cornstarch; Juice from 1/2 lemon; Chopped fresh parsley and lemon wedges, for garnish