Prepare the pasta noodles as per packet directions.
Dry off the chicken chunks with some paper towels then season them with a couple pinches of salt and black pepper powder. Put the 1 tbsp flour into a sieve and gently dust the flour over the chicken pieces.
Heat half the butter and oil in a pan, then add the chunks of chicken and fry on high heat until golden on both sides. Do this in batches if necessary, do not crowd the pan. The aim here is to brown the chicken and build up layers of flavour, not to fully cook the chicken. Once the chicken pieces are golden, remove them onto a plate.
In the same pan, add the remaining oil and butter and let it heat up, then add the onions and fry until slightly golden. Next, add the sliced mushrooms and cook for a couple of minutes on medium heat.
Add in the garlic paste and stir it in until fragrant, then add the tomato paste followed by the black pepper, paprika powder and chilli powder. Give everything a good mix, then add the stock or water, sugar and the vinegar or lemon juice. Simmer on medium heat for about 3-5 minutes until the sauce thickens slightly then add in the chicken pieces with their juices and give it all a good mix. Turn the heat down to low, cover and let everything simmer for about 5 more minutes.
Finally add the sour cream and simmer gently while stirring for another couple of minutes. Make sure to check and adjust the salt.
Turn off the heat and sprinkle the chopped coriander/parsley. Serve the chicken stroganoff over pasta, rice or with mashed potatoes or fries.