Dust the chicken with flour.
Fry in spray oil until golden all over.
Remove and set aside.
Pour in the Marsala wine.
Bubble until reduced by half.
Pour in the stock.
Add leeks, parsley, chicken and fennel.
Cover and simmer over a low heat 10-15 minutes.
Add asparagus in final 2 minutes.
Using a slotted spoon, remove the chicken and veg.
In a small bowl mix about ½ the egg with the lemon juice.
Add about 2 tablespoons of the hot cooking liquid slowly, stirring well.
Slowly add this mixture to the pan, mixing it in.
Return the chicken and veg to the pan and gently warm through taking care not to scramble it.
Garnish and serve.