Heat oil in a large non-stick frying pan and soften onion for about 5 minutes.
Add the paprika and garlic, then cook for 1 min more. Add the mushrooms and cook on a high heat, stirring often, for about 5 mins.
Pour in the stock and Worcestershire sauce. Bring to the boil, bubble for 5 mins until the sauce thickens, then turn off the heat and stir through the soured cream. Make sure the pan is not on the heat or the sauce may split.
Cook the rice following pack instructions, then serve with the stroganoff.