In a large pot, fry the chicken breasts in the oil, skin side down until browned.
Add the onion and fry until translucent.
Add the warm stock, about half of the boiling water, herbs & spices and simmer for 20 to 25 minutes until the chicken is tender.
Remove the chicken portions from the stock and let it cool down a bit. Bring the stock up to a boil and add the potato cubes and then the frozen veggies.
Season with salt and pepper.
Let the veggies cook in the stock until they are tender, but not overcooked. Approximately 10 to 15 minutes.
In the meantime, debone the chicken and chop the meat into cubes or strips. Don't make the chopped chicken too fine.
Once the veggies are tender, add the chicken back to the stock and bring it to a simmer. You can add the other half of the boiling water if the stock has cooked away.
Dissolve the flour or cornstarch in the cold milk, making sure there are no lumps. Pour the flour slurry into the soup gradually while stirring.
Keep stirring while the soup thickens.
Once the soup is thick, check the seasoning, adding salt or pepper as needed.
Serve warm with soft buttered breadrolls or warm crusty bread.