- Put the vinegar, salt, rosemary, bay leaf and garlic clove on a saucepan with 150mls water and bring to the boil.
- Reduce to a fast simmer and cook for 5 minutes.
- In the meantime bring a saucepan of salted water to the boil and cook the mushroom slices for 2 minutes then drain.
- Add the mushrooms to the vinegar mix and let cool. You can store them in the fridge for a few days.
- Before serving, drain and toss with olive oil.
- In a bowl, mash the avocado until smooth with the lime juice then mix in the mayonnaise and season with salt to taste. Set aside.
- Cut the onion in quarters and finely slice. Place in a bowl of water and leave for 10 minutes, then drain thoroughly.
- Season the steak with salt and pepper. Heat the barbecue or grill to very hot and grill for about 2-4 minutes each side until done to your liking. Rest for 5 minutes then slice thinly.
- Heat the tortillas as directed on the packet.
- To serve place a few pieces of steak on a tortilla with some avocado mayo, onion and watercress and top with pickled mushrooms and serve with hot chilli sauce.
Pickled mushrooms are also great as an accompaniment to barbecues, roasts, in salads or as part of an antipasto platter.