Most cooks know that a squeeze of lemon juice will keep fresh-cut fruit and certain vegetables—like artichokes—from turning brown; the acid prevents enzymes from oxidizing the pigments. And a spoonful of vinegar added to poaching water will help a poached egg to hold its shape; here, the acid causes the egg proteins to coagulate. But when Syrian cooks blend together eggs and artichokes, with no acidity in sight, the enzymes in the artichokes react with the high iron content of the egg yolk; the eggs lose their buttery yellow color, and the whole dish turns a sort of pewter gray. The flavor is fine, but oh, that look. In this case, the solution is unscientific: Cook quickly and serve immediately; or sprinkle the dish liberally with parsley, and eat before the sun comes up.