Heat a frying pan or wide saucepan over medium heat and add the olive oil. Once hot, add the onion along with a pinch of salt and cook gently for 5–7 minutes or until soft.

Add the garlic to the pan and cook for 2 minutes; then add the mushrooms. Continue to cook gently for 5–6 minutes, or until the mushrooms are tender and golden brown.

Add the mustard and paprika, mixing well to coat everything. Add the stock, stirring as you pour it, and simmer gently for 5 minutes while cooking the rice.

Cook the rice according to the packet instructions in a separate saucepan until tender.

Once the rice is cooked, remove the mushrooms from the heat, stir in the soured cream along with the juice of two lemon wedges, and mix it together. Taste and add salt and pepper as needed.

Serve the stroganoff with the rice and the remaining wedges of lemon on the side.