Ingredients
300g onions, sliced 
2 tbsp oil 
2 garlic cloves, minced 
2 tsp paprika 
500g mixed mushrooms, sliced 
1 tsp Dijon mustard 
1 tbsp tomato purée 
200ml mushroom stock 
150ml sour cream plus 4 tsp
½ tbsp lemon juice 
1 tsp sherry vinegar
15g parsley, chopped 
Salt 
Pepper
2 tsps porcini powder (optional)

Method
Put a wok or large frying pan on a medium heat and add 1 tbsp of the oil.  Add the onions and seasoning and cook for around 10 minutes until caramelised.  Add the garlic and the paprika and cook for another 2 minutes.  Put into a bowl and with kitchen towel just clean out your pan a little.   

Add 1 tbsp of oil to the pan and cook the mushrooms on a high heat until the juices come out of the mushrooms and gets reabsorbed - this will take 5-10 minutes depending on the mushrooms and how brave you are with the heat.  When you first start cooking you will need to constantly stir.  Season with salt and pepper.

Put the onions back into the pan with the mushrooms and the porcini powder. Add the tomato purée and mustard and stir, add the stock and thoroughly stir again and then bring to the boil. Reduce the heat and add the sour cream, lemon juice, sherry vinegar and the parsley. 

Check seasoning and serve either on rice or pasta with 1 tsp of sour cream and a dusting of paprika.