In a large pot on the stove, combine the water and salt. Bring to a boil.
Whisk in the oats. Stir in the apples. Cook 30 minutes, uncovered, stirring occasionally.
Divide the oatmeal into dishes, season to taste with brown sugar. Add other toppings as desired.
Assemble the oatmeal bowls in containers with lids. Add toppings, cover, and store in the refrigerator for up to 4 days. Alternatively, chill the dishes completely and freeze for up to 6 weeks.
Serving size is dependent on personal tastes and appetites, but one batch should serve 4 to 8 people.Promptly store leftovers in an airtight container in the refrigerator, for up to 3 days.Nutritional values are approximate, based on 1/8 the recipe, and do not include additional toppings.