There's a big hole in the Hawaiian food market and it isn't just the empty imu at Tam's Kalua Service in 'Aiea.

Alvin Tam, owner of what may be O'ahu's only licensed imu kalua pig wholesaler, cooked his last pig at the end of May, leaving many restaurants without a source of the Hawaiian food staple. The closure has forced restaurants to either make their own kalua pig or find other producers who can match the flavor of Tam's pig, which was cooked the traditional way underground.

"It's a great impact because it's a major item on our menu," said Alan Young, owner of Young's Fish Market in Kapalama.

Tam's kalua pig has been on the Young's Fish Market menu since Young's parents added Hawaiian food to their fare about 50 years ago. Young was a rare customer because he ordered whole pigs — five to six a week — cooked in Tam's imu.

Tam also cooked pork butts for customers looking to save money, but the end result was still a tastier product than what is produced in an oven.

"My customers are used to a certain type of pig," Young said. "That's why we commanded a higher price because it was the imu pig."

Tam's Kalua Service was founded by William Tam in 1950 in 'Aiea. Alvin Tam, 62, has worked in the business all his life and took over in the 1980s, but said his health forced him to slow down over the years and eventually retire.

"This is hard work," Tam said. "This is not easily done, and there's plenty of physical work with the imu. You can only automate so much."

The publicity-shy Tam said that during its peak the business produced about 4,000 pounds of kalua pig each week. But with the introduction of the cheaper oven-cooked kalua pig and the strain the work put on his health, business declined over the years.

"At one time I had everybody, a lot of restaurants. But this last couple of years I was just keeping it small so I could handle it myself," Tam said. "But then it was getting hard to handle myself."

Tam's pigs were cooked in concrete pits because federal health regulations forbid the use of dirt. But everything else was done in the traditional way. No Liquid Smoke here.

"There's only one way to do it, and it's this way if you want that taste," Tam said. "You couldn't get the taste out of an oven."

At Ono Hawaiian Foods in Kapahulu, owner Vivian Lee said Tam's kalua pig has been sold at the restaurant since it opened about 45 years ago. Lee said her usual order was from 225 to 250 pounds a week.

"Mr. Tam's kalua pig is always good," Lee said. "Even if it's expensive, it's always good. The others don't taste as good. The imu kalua pig is better."

Both Young and Lee have stockpiled as much of Tam's kalua pig as they could cram into their freezers. But they know that they will soon have to replace it with an alternative.

Lee already has turned to Hawai'i Food Products, which sells its food under the Ono Ono brand name. Young said he's still experimenting with recipes to create his own kalua pig.

"People will still want the item, but they're going to have to get used to what comes out," he said.

Delia Soliven, sales representative at Hawai'i Food Products, said she's already received calls from Tam's longtime customers. Soliven said her company cooks the kalua pig "imu style" in an oven, but uses no Liquid Smoke.

"Tam's was the last of the old style, but we come very close," Soliven said.

Tam said he is adjusting to his new life and hopes to turn the business over to his son, who has worked with him. But he said he's not sure if anyone would want to carry on the business.

"I'm sure I'm going to get guys who want to take over, but I want to see if they can do it or not. It's harder than just throwing (the pig) into the oven," Tam said. "But I want to take a good rest first. I don't want to jump into anything too fast."

His customers are hoping that someone will continue making the imu kalua pig.

Young said he will wait for the final word from Tam before investing in ovens and employees to make his own kalua pig.

"It's tough when the old-style of cooking is dying out," Young said. "That's what makes this kind of business a little tougher than others. We have to deal with all local items, and our supplies are all local."

Reach Curtis Lum at culum@honoluluadvertiser.com.