Heat the grill to high. Heat the oil in a medium-sized, non-stick frying pan, add the mushrooms and fry over a high heat for 3 mins. Squeeze the sausagemeat out of their skins into nuggets, add to the pan and fry for a further 5 mins until golden brown. Add the garlic and asparagus and cook for another 1 min.

Whisk the eggs, soured cream, mustard and tarragon in a jug. Season well, then pour the egg mixture in to the pan. Cook for 3-4 mins, then grill for a further 1-2 mins or until the top has just set with a slight wobble in the middle. Serve with the salad leaves, if you like.