Rinse the beans in a sieve/colander under cold running water, then tip into a large bowl and add 2 litres of cold water to cover. Pop in the piece of kombu, if using. Cover with a clean towel and leave for a minimum of 8 hours to soak overnight.

After soaking, drain then rinse again under running water.

Preheat the oven to 150°C fan-forced (170°C conventional).

Tip the soaked and rinsed beans into a medium oven proof casserole pot with lid and cover with water. Bring to the boil on stove top, then drop to a simmer and cook for 40 minutes until tender. Drain and set aside.

Return the pot to the stove over a low-medium heat. Add the oil, onion and garlic and cook for 6 minutes, stirring occasionally until aromatic.

Add the cooked beans and tomatoes, then fill the can with water and add to the pan along with the stock. Add the bay leaves, thyme sprigs and 2 tablespoons of vinegar.

Combine the mustard powder, spices and sugar in a small bowl, then stir into the pot to combine.

Add the ham hock, increase the heat and bring to the boil, then drop to a simmer.

Place a round sheet of baking paper over the top of the ham hock and beans, then cover with a tight-fitting lid.

Transfer the casserole pot to the oven and bake for 2 hours, checking if the beans are very tender by pressing with a fork.

Continue baking for another half hour if the beans don't yield satisfactorily to your fork and then test again.

Taste and adjust seasoning if needed with extra salt, a grind of pepper and stir through the remaining tablespoon of vinegar.

Remove the baking paper and fish out the hock, then cover the pot with a lid and set aside to rest.

While resting, pull away and separate the meat from the hock bones. Stir meat through the bean mixture and fish out the bay and thyme twigs.