1. Wash, but do not peel the vegetables. Dice coarsely or slice using the medium slicing blade of a food processor.
2. Saute in hot oil until vegetables are tender.
3. Combine the vegetables with water in a large pot; cover and bring to a boil; uncover, reduce the heat, and cook at a rapid simmer until the liquid is reduced by half.
4. Strain the stock, and discard the vegetables. Freeze the stock in portions suitable for your familys needs.