Preheat the oven to 200°C/gas mark 6

Start by massaging the bones with a little oil and roasting in the hot oven for about an hour. The bones should have turned a deep golden brown – don’t be too afraid of burning them as the darker the colour, the deeper the flavour, so a little bit of charring is fine

In a large stockpot, pour in a good glug of oil and add your onions, celery, leek, carrot and garlic (cut-side down). Sweat down until nicely caramelised, about 15 minutes

Once the vegetables are nicely caramelised, add the herbs and spices, stir in the tomato purée and cook out for a further 5 minutes

Add the roasted bones to the pot and deglaze the roasting tray with some of the wine. Scrape all the flavour from the bottom of the pan using a wooden spoon or spatula. Pour the delicious juices into the stock pot and add the rest of the wine. Bring to a simmer

When the wine has reduced by three-quarters, top up the pan with cold water, just enough to cover the bones. As a rule of thumb, you will need roughly the same weight of water as bones – just ensure the bones are completely submerged in liquid

If you're using them, add the pig's trotter and/or the sheet of kombu

Bring the stock to the boil, skim off the scum with a ladle and turn down the heat to a low simmer. Simmer away for 4–6 hours, regularly skimming the rising impurities from the top. It is important to slowly simmer and not rapidly boil, as you need the time to build up flavour

Strain the liquid through a muslin cloth or fine sieve, then transfer to a storage container and chill down as quickly as possible. Alternatively, return to the pan and reduce down further to create a thicker, glossier sauce known as demi-glace, which is good for gravies or using as a concentrated stock