On a hot fire that still has a few flames, heat up a cast iron pot.
Add oil and chicken pieces skin side down and brown the chicken pieces.
Remove the chicken pieces from the pot and add the chopped onion. Stir the onions and fry until translucent and slightly browned.
Add the garlic, ginger and fresh chilli and fry until fragrant. Be careful that the garlic does not burn.
Add the curry paste and chilli powder and fry for another few minutes.
Add the tin of whole tomatoes as well as the tomato paste and stir to break up the tomatoes.
Add the chicken stock and return the chicken pieces to the pot.
Cover with the lid and let simmer for at least 30 minutes on a low fire. There should be no need to peek.
Open the pot after about 30 minutes and give it a careful stir. Add the vegetables starting with the potatoes and hard vegetables first and the quick-cooking veggies like mushrooms last.
Season with salt and pepper to taste. At this point you should also make sure that there is enough moisture left in the pot. If the sauce level is below the bottom layer of veggies, add a bit of water until the hard veggies like potatoes are just covered. Replace the lid and leave for another 30 minutes.
During this time you are allowed to look into the pot to check sauce levels and that the bottom is not burning. Do not stir much as that will break up the veggies.
Once all your veggies are tender, you can leave the pot cooking without a lid to reduce the sauce a bit before serving. At this stage it would also be good to check the seasoning. A large pot holds quite a lot of food and you might have to add more salt. Depending on how much tomato you've added, you might also need to add a sweetener like sugar or chutney.
Carefully remove the pot from the fire using oven gloves and put the pot on a stable heatproof surface. Serve the potjiekos on rice or other starch of your choice.