Beat yolks slightly. Gradually add the chicken broth.
Add water chestnuts to the beaten egg yolks, then add cornstarch and salt.
Heat lard in a frying pan until vapor rises from the surface, remove pan from heat and pour yolk mixture in immediately. Mix with a spatula. If egg yolk does not properly solidify and settle in the lard, then place back on heat to increase temperature. Use care not to overheat. Transfer to a serving dish when the mixture begins to thicken. Sprinkle on the minced ham.