Microwave Directions. 1  Combine water, oat bran and salt in medium (1-1/2 qt.) microwaveable bowl. 2  Microwave on HIGH. - 3  1 serving: 2-1/2 to 3 minutes. - 4  2 servings: 4-1/2 to 5-1/2 minutes or until thickened, stirring halfway through cooking. 5  Stir before serving.