Here's my Mums original recipe...
3 Cups of Apple Cider Vinegar
1/2 Cup of Fresh Lemon Juice
2 Fresh Bay Leaves
2 Sprigs of Fresh Thyme
2 Cloves of Garlic thinly sliced
3 Small Red Thai Chilli
1 kg Button Mushrooms
Combine all of the ingredients besides the mushrooms in a large saucepan. Bring to the boil, reduce to a dinner and add the mushrooms. Simmer for 15 minutes. Pour into hot sterilised jar and seal while hot. These will last for 6 months, refrigerate after opening.