Onsen tamago — which literally translates to “hot spring egg” — is a soft-cooked Japanese egg preparation that pays homage to the country's many hot springs. Locals and tourists alike participate in the tradition of communal bathing in these volcanic springs, and onsen tamago were originally cooked directly in the warm water.

Back in the day, whole eggs in the shell were left in the water at onsen spas to cook for hours. The gentle, stable temperature of the water cooks the egg whites to a custardy texture while the yolk remains runny, and the eggs are then served in a broth of dashi, soy, mirin, and sugar, garnished with scallions or the herb mitsuba.

Today, you can cook onsen tamago without a hot spring by cooking whole eggs at 170 degrees F in a heavy pot for about 20 minutes. You can also cook them in a rice cooker at 160 F for 20 minutes, or in a sous vide machine for about 45 minutes; once the time is up, enjoy the eggs as a superb ramen topping or as a snack.