Preheat oven to 200°C. Apply tomato paste over chicken bones. Place chicken bones and vegetables (onion, carrot & celery) onto a baking tray and roast in the oven for 40 minutes. If your tray is not big enough to accommodate all the ingredients, separate the chicken and vegetables into 2 different trays, and roast the chicken bones for 40 minutes, but the tray of vegetables for 20 minutes. Remove from oven.

Add roasted ingredients and the remaining herbs & spices (black peppercorns, thyme & bay leaves) into a big stock pot. Add 5 litres of room temperature water and bring the pot of water to a boil. Thereafter, lower the fire so that the water is only simmering (small bubbles breaking the surface). Simmer cook for about 2-3 hours. Skim off any scum you see appearing at the surface. Towards the end, season the stock with salt according to your preference.

Remove the ingredients, and strain the liquid into large bowls. Cool the stock down as quickly as possible by placing the bowls into even larger bowls of ice-cold water. Once cool, you can skim any layer of fat that accumulates on the surface. Pour the chicken stock into ice cube trays and freeze for a few hours. Once frozen, remove the stock cubes and keep in a ziploc bag. The stock cubes can last for a few months in the freezer.