Sephardic Long-Simmered Eggs

Huevos haminados, a Sephardic specialty of the Passover table, is made with eggs long simmered in a low-temperature water bath filled with red onion skins or Turkish coffee grounds for up to twelve hours at 160°F. (Salmonella in eggs are killed at 140°F after one hour.) I do this in a slow-cooker. The eggshells emerge in beautiful maroon to purple hues while the yolks and whites attain a unique flavor.

Serve with salt and ground cumin along with a salad, or with long cooked f