Thinly slice the shallot and finely chop the garlic. Cut off the woody ends of the asparagus and discard them. Cut the asparagus stalks in half.
Heat the oil in a large, shallow pan and gently fry the shallots for 5 minutes.
Add the garlic and thyme and stir for a minute, then pour in the chicken stock.
Bring to the boil, then add the asparagus pieces. Cook for 3 minutes, then add the chicken pieces and cook for a couple of minutes to warm through. Add the lemon zest and juice.
Serve with chopped parsley scattered on top.