Bring a pan of salted water to the boil. Whip the cream with the lemon zest, lovage, salt and pepper until mousse-like and refrigerate.
In a separate bowl, mix the oil and vinegar. Cut the asparagus tips to two inches in length and blanch in boiling water for 1½ minutes. Slice the stalks with a potato peeler to ribbons and dip in the vinegar bowl. Add the boiled asparagus tips and toss together.
Serve with the clotted cream mousse. Gently dip each flower in the vinaigrette.