Heat the olive oil in a medium saucepan. Add onion, carrots, turnip, and celery. Cover the saucepan and cook the vegetables on a low heat for 25 minutes. Stir frequently.
When the vegetables are cooked, add tomato, bay leaf, thyme, parsley, peppercorns, clove, salt, bullion, and water to the saucepan. Cover the pan and allow the mixture to simmer for 1 hour.
At the end of the hour, taste the stock. Add another bullion cube if needed, stir the stock, and continue cooking for another 10 minutes. When the stock is done, pour the mixture through a fine strainer into a bowl.
The vegetable stock can be used immediately or cooled and stored in the refrigerator. It will stay fresh for several days if kept in glass jars.