SANTA ANA — The Red Onion restaurant chain, which two years ago paid the steepest civil fines ever levied in Orange County for health and safety code violations, agreed Friday to a new record payment of $380,654 for repetition of most of the old violations at its four restaurants in the county.

The violations--at Red Onion restaurants in Santa Ana, Huntington Beach, Fullerton and Orange--included vermin infestation, poor food-storage temperatures and generally unsanitary conditions, according to an injunction filed in Superior Court by the district attorney's office.

In a stipulated settlement with prosecutors, the restaurant chain agreed, in addition to the fine, to improve sanitary conditions at the four Orange County restaurants, hire a food and safety consultant, spend $50,000 in improving equipment, and put its management and staff through training approved by the Orange County Health Care Agency.

Dist. Atty. Michael R. Capizzi said that if the Red Onion doesn't improve conditions this time, his office would try to close the restaurants in Orange County.

"It's time we skinned the onion," Capizzi said. "This is an aggravated case that was further aggravated by the 1988 violations. We think this fine should ensure protection of the public at these restaurants. But three strikes and they're going to be out."

The Red Onion, without an admission of wrongdoing, agreed in 1988 to pay $320,000 in fines and another $55,000 in court costs and attorney's fees for health and safety violations, plus a violation of the state fire marshal's code on overcrowding. It also agreed then to address each of the violations cited.

But Deputy Dist. Atty. Jan J. Nolan, head of consumer and environmental fraud, said the new violations showed that the restaurant management had made almost no progress.

"We couldn't tell that they had done anything at all in the two years since the last injunction," Nolan said. "The problem is basically just general filthy conditions."

The Red Onion chain also made no admission of wrongdoing in the new injunction. In a statement, the company said its restaurants already meet high health standards.

"We settled this matter because it is more economically beneficial to the company to run restaurants than to spend time in court," said Red Onion attorney Stephen W. Solomon. "We continue to serve the finest Mexican food in Orange County, and we maintain the strictest standards for operation and cleanliness of all facilities."