In a large saucepan or the pot of a pressure cooker, add the oil and sauté the onion, garlic, carrot and ginger until softened – approx. 5 minutes.
Add the tomato paste, parsley, peppercorns, bay leaves and salt and sauté for 5 minutes. Add the bones. For a stove top: fill the saucepan with enough water to just cover the bones. Simmer for at least 16-24 hours or until the bones are falling apart. For a pressure cooker: fill the pot with water until the max line is reached. Cook on high pressure for 4 hours and allow the pressure to naturally release.
Season the stock to taste with salt and set aside to cool until warmish.
When cool enough to handle, strain and divide between airtight containers. Chill in the fridge for at least 2 hours, or until the stock is jellified and fat has formed a solid lid.
Spoon off the fat and reserve it for another use (like roasting vegetables, toasting bread, or frying potatoes).
If using fresh bones for this recipe, blanch them in salted water first to remove any impurities.