To make sauce, beat egg yolks until thick and light colored. Mix in water and transfer to top of double boiler set over barely simmering water. Heat and stir 2-3 minutes until warm, not hot, and eggs have begun to thicken. Add butter, 2 tablespoons at a time, beating continuously until well blended. Cook, beating 2-3 minutes until sauce thickens enough to coat back of spoon. Remove from heat and stir in 1/4 teaspoon salt, pepper and lemon juice. Serve immediately with zucchini sticks.

NOTE: Vegetables that may be substituted for zucchini include artichoke hearts, carrot stocks, cauliflower florets, parsley sprigs, sliced parsnips, and sweet potato sticks.