Sauté the onions in some lard in a pan on a low heat with a good pinch of salt until they become very soft and turn a light golden colour – around 10 minutes.
Add the TV paprika or peppers to the pan and cook until the peppers begin to soften a little. Add the chicken thigh pieces and allow to cook gently until the chicken turns white. Add the garlic and the tomato and cook for a further 2 minutes.
Remove from the heat and add the sweet Hungarian paprika, and stir well.
Return the pan to the heat, adding about 100ml of water to the pan (or enough just to cover the chicken), cover the pan and simmer for about 30 minutes on a low heat, stirring occasionally. Do not let the liquid boil.
Whisk the sour cream (or tejföl) and the flour in a bowl until combined, ensuring there are no lumps. Add to the pan and stir well, and cook for another 5 minutes or until the sauce has reached a smooth creamy consistency.
Garnish with some finely chopped parsley and serve.