Ingredients

• 20g butter
• small amount onion, finely chopped
• 500g button and chestnut mushrooms, halved
• 60ml water
•   salt and pepper
• 1 teasp balsamic vinegar
•   parsley
• 1 teasp tarragon
• 1 teasp grated lemon zest
• 20g butter, to thicken sauce
• 4 slices bread, toasted
•   cheese

Method

1. Melt 20g butter in a saucepan. Add a small amount of finely chopped onion, 500g halved button and chestnut mushrooms, 60ml water, and salt and pepper.
2. Cover and cook, stirring occasionally, for approximately 10–15 minutes.
3. Stir in 1 tsp balsamic vinegar, parsley, tarragon (1 tsp), and 1 tsp grated lemon zest.
4. Whisk in 20g butter to thicken the sauce.
5. Toast 4 slices of bread, cover with a slight layer of cheese, then top with the mushrooms and serve.