A nice change of pace for asparagus in season. The sauce can be kept warm over hot water while the asparagus cooks.
To make the sauce, combine water, lemon juice, 4 tablespoons of the fruit juice, the fruit rind, salt, and pepper in a saucepan. Reduce over moderate heat to 3 or 4 tablespoons. Add the egg yolks one at a time, whisking over low heat until very thick. Remove from heat and slowly dribble in butter, whisking constantly Slowly add the remaining fruit juice, a teaspoon at a time. Strain if you wish (Bill Sammons prefers the rind left in). If necessary, keep sauce warm over a pan of warm water while asparagus cooks. Remove tough ends of asparagus and cook tips only 4 to 7 minutes, until bright green but still slightly crisp. When asparagus is ready, place sauce in a warmed ceramic bowl and serve with the asparagus.