There were long lines outside several McDonald’s outlets in Singapore last June. The coveted menu item was a limited edition burger—a fried chicken patty smothered in salted egg yolk gravy. Salted egg yolk mania has reached a fever pitch in Singapore, but this old Chinese method of preserving eggs in brine has been around for at least 1300 years. Traditionally eaten in congee for breakfast, you can now find it in all sorts of unexpected foods in Singapore. Think of it as the Southeast Asian answer to salted caramel.

The ingredient is valued for its granular texture and oily richness cut with a satisfying salty flavor. There are now onion rings and French fries tossed in salted egg yolk sauce, potato chips or popcorn dusted in salted egg yolk flavoring, and salted egg yolk custard oozing from chocolate lava cakes or folded into ice cream.

Singapore cocktail bar Nutmeg & Clove even serves a salted egg yolk cocktail. The drink, called Old Harbour, combines it with red dates, port wine, and nutmeg to create a sweet and savory take on a classic flip. “The flavor is just ridiculously good,” says owner Colin Chia. His cocktail menu is based on the history of Singapore, so incorporating salted egg yolk seemed like a natural fit. “Salted egg yolk is a staple of Singapore, of the Chinese,” he says.

 

As the country’s largest ethnic group, the Chinese have had a profound influence on Singapore’s cuisine, but other groups like the Malays and Indians have left a significant mark as well. Julien Royer, the French-born chef of Odette Restaurant, had trouble defining the local palate when he first arrived in Singapore. “There was such a huge diversity of different cuisines available everywhere,” he recalls, “But I soon noticed that egg was an ingredient that recurred in a lot of Singaporean dishes.”

From kaya toast served with soft-boiled eggs for breakfast, to the sliced boiled egg garnishing mee siam vermicelli noodles, to the whole egg cracked and stirred into the sauce of chili crab, Royer believes this low-cost protein alternative to meat perfectly complements the spicy and smoky flavors that Singaporeans enjoy so much. The strong Chinese culinary influence combined with an intense love of eggs means salted yolk mania has taken off in Singapore like nowhere else.

Cantonese dishes like fried crab or prawns tossed with salted egg yolk or mooncakes and steamed buns filled with the custard have been popular in both Hong Kong and Singapore for years. So it was only a matter of time until pastry chefs began stuffing French croissants with it.  Pang Kok Keong, the chef and owner of Antoinette in Singapore, credits Urban Bakery in Hong Kong with making the first one.

Keong has since recreated it for his French bakery and cafe in Singapore. This crackly croissant, injected with a golden-orange salted egg yolk custard made from milk, sugar, and butter was an instant hit. Several other bakeries are making it too, but Antoinette’s Salted Yolk Lava Croissant remains one of the most sought-after because it uses real salted egg yolk instead of a powdered substitute.

Chefs across Singapore have been playing with the yolks ever since the croissants appeared on the scene, and they continue to pop-up in unexpected places. McDonald’s may have phased out the salted egg yolk burger, but everything else seems here to stay. “I believe this is not a trend,” says Keong. “This is a mainstay. Singaporeans love their salted egg. Period.”