Pre-heat the oven to 200°C. Coat the bones and hooves in half the oil and roast in a hot oven until brown, turning the bones frequently to ensure an even colour. When the bones are roasted, drain and place in a heavy-based pot and cover with the cold water. Bring to the boil, reduce the heat to a simmer and cook for 30 minutes, skimming frequently to remove the impurities that float to the surface. Pour the remaining oil into the same tray in which the bones were roasted. Add the vegetables and return to the oven to cook for 20 minutes until caramelised. Stir the vegetables and loosen the sediment left behind by the bones. Mix the tomato paste through the vegetables and continue to cook for a further 10 minutes. Add the vegetables to the stock and continue to cook for a further 8 hours or until the stock has reduced by two thirds. Skim frequently. Pass the stock through a coarse sieve to remove the bones and vegetables. Once again, pass the stock through a fine sieve into a clean stainless steel container and refrigerate to solidify any fat that may rise to the surface. Remove the fat before using.